Evacuation, Invacuation and Lockdown: Understanding the Difference in Your Organisational Planning.

When organisations think about emergency planning, evacuation is often the first response that comes to mind.

If something goes wrong, the assumption can be simple:

Raise the alarm. Get everyone out.

But in a hostile incident or other serious emergency, getting people out of a building is not necessarily the safest option.

The appropriate response depends on the circumstances.

Sometimes people need to leave.

Sometimes they may be safer moving into a building or protected internal area. Sometimes the safest response may be to secure people where they are and restrict movement.

This is why organisations should understand the difference between evacuation, invacuation and lockdown, and consider how each may fit within their wider emergency and protective-security arrangements.

What is evacuation?

Evacuation means moving people away from a building, location or area of danger, normally to a safer location.

It is familiar to most organisations through fire evacuation procedures.

For example, if there is a fire inside a premises, occupants may be instructed to leave using designated escape routes and move to an assembly or other safe area.

However, evacuation is not automatically the correct response to every emergency.

The key question is:

Where is the threat, and where does evacuation take people?

If a threat is inside a building, moving people away from that building may be appropriate.

But if the threat is outside, directing everyone out of the building could potentially expose them to greater danger.

That is where alternative protective actions need to be considered.

What is invacuation?

Invacuation generally means moving people into a building or safer internal location when remaining outside may present a greater risk.

It can therefore be thought of as the opposite direction of evacuation.

Imagine an incident occurring close to your premises.

If people are outside, on a car park, in an external courtyard or approaching the building, moving them into a suitable secure area may provide greater protection than telling them to disperse.

The precise arrangements will depend on the organisation and its premises.

For example, an organisation may need to consider:

• Which areas provide the greatest protection?

• Can doors and access points be secured?

• Can people be accounted for?

• Can staff communicate instructions clearly?

• Are there people who may need additional assistance?

• Can the organisation continue to monitor the situation?

• What happens if the situation changes?

Invacuation should therefore not simply mean “everyone get inside.”

The organisation needs to understand where people should go and what they should do once they get there.

What is lockdown?

Lockdown involves securing people within a protected area and restricting movement or access because of a serious threat.

The term is sometimes used very broadly, but effective lockdown arrangements should be based on the circumstances and the organisation’s risk assessment.

Depending on the situation, this could involve measures such as:

• securing doors and access points;

• moving people away from exposed areas;

• preventing unauthorised entry;

• controlling internal movement;

• communicating clear instructions;

• maintaining situational awareness; and

• coordinating with emergency services where appropriate.

  
  

Lockdown is therefore not simply about locking the front door.

It is about creating a safer environment by controlling access and protecting people from a threat.

The decision isn’t always obvious

One of the biggest challenges in emergency planning is that the safest response can change depending on the circumstances.

Consider three simplified scenarios.

Scenario 1: Threat inside the building

If there is a serious threat inside a premises and a safe route away from the danger is available, evacuation may be appropriate.

The organisation’s priority is to move people away from the threat.

Scenario 2: Threat outside the building

If a serious threat is occurring immediately outside the premises, sending everyone onto the street may not be appropriate.

Invacuation may provide a safer alternative, depending on the circumstances.

Scenario 3: Immediate hostile threat

If people are already inside a building and there is an immediate threat requiring them to remain protected, a lockdown response may be appropriate.

The organisation may need to secure areas, restrict access and provide clear instructions until the situation changes or emergency services provide further direction.

These examples are deliberately simplified.

Real incidents are dynamic.

The appropriate response will depend on the nature of the incident, the location of the threat, the characteristics of the premises and the information available at the time.

Why this matters for Martyn’s Law

The Terrorism (Protection of Premises) Act 2025, commonly referred to as Martyn’s Law, is intended to improve the protection of the public from terrorism.

For organisations within scope, this means thinking seriously about how they would respond to a terrorist attack or other relevant act of terrorism.

However, it is important not to overstate what the legislation requires.

Martyn’s Law does not mean that every organisation must have an identical evacuation, invacuation or lockdown procedure.

Instead, organisations need to consider the risks relevant to their premises and activities and put appropriate measures and arrangements in place.

That should sit alongside existing emergency planning rather than being treated as an entirely separate exercise.

For many organisations, there will already be procedures covering matters such as:

• fire

• medical emergencies

• severe weather

• suspicious packages

• violence

• security incidents

• loss of utilities

• evacuation.

  
  

The opportunity is to consider whether those arrangements adequately reflect the range of threats the organisation could reasonably face.

Don’t confuse fire evacuation with every emergency response

This is particularly important.

A fire evacuation procedure is designed primarily around the risks associated with fire and smoke and the need to move people to safety.

A hostile attack can present a very different set of circumstances.

For example, an instruction to evacuate may be entirely appropriate in one situation but potentially dangerous in another.

That does not mean fire procedures should be abandoned.

It means organisations should recognise that different emergencies may require different protective actions.

Emergency planning should therefore avoid relying on a single instruction for every conceivable incident.

Communication is critical

Even the best plan can fail if people don’t understand what they are being asked to do.

During a serious incident, people may be frightened, confused or receiving conflicting information.

Instructions therefore need to be:

Clear. Simple. Practised.

Staff should understand their responsibilities and know how emergency instructions will be communicated.

Organisations should consider how they would communicate with:

• employees;

• customers;

• visitors;

• contractors;

• vulnerable people;

• people with disabilities; and

• anyone who may not be familiar with the premises.

Communication arrangements should also consider what happens if normal systems such as telephones, internet access or public address systems are unavailable.

What happens when the situation changes?

Another important consideration is that an emergency response is not necessarily static.

A situation can develop.

For example:

Evacuation → changing threat → sheltering or invacuation

or:

Invacuation → threat changes → evacuation

The initial decision may therefore need to be reviewed as new information becomes available.

This is why emergency planning should focus not just on writing procedures, but on developing decision-making capability.

People responsible for managing an incident need enough understanding to recognise when circumstances have changed and when a different protective action may be required.

Practical questions organisations should ask

Rather than simply asking:

“Do we have an evacuation plan?”

consider asking:

1. What threats could reasonably affect us?

Consider the nature of your premises, location, activities, occupancy and operating environment.

2. Where would people be safest?

Would moving outside actually take people away from danger?

Could an internal location provide greater protection?

3. What would we do if the threat was outside?

Have you considered how people entering, leaving or congregating outside the premises would be managed?

4. What would we do if the threat was inside?

Are there appropriate routes, procedures and communications for moving people away from danger?

5. How would we secure the building?

Could doors, access points and other relevant controls be used effectively?

6. Who makes the decision?

People need to understand who has responsibility for initiating emergency procedures and how decisions will be communicated.

7. How would we communicate?

Can you provide clear instructions to staff, customers and visitors quickly?

8. What happens to people requiring additional assistance?

Emergency arrangements should take account of the needs of people who may require assistance to move, shelter or understand instructions.

9. Have the arrangements been tested?

A procedure sitting in a folder is not necessarily an effective procedure.

Exercises, briefings and training can help identify practical weaknesses before an incident occurs.

Proportionate planning is the objective

There is a temptation when discussing protective security to produce increasingly complicated plans.

More pages do not automatically mean better security.

For many organisations, particularly smaller businesses and community-facing premises, the most valuable approach may be a simple, proportionate and well-understood set of arrangements.

People should know:

What might happen.

What they should do.

Who is responsible for making decisions.

How they will receive instructions.

Where they should go.

And importantly:

When the response may need to change.

The three words to remember

A useful starting point is:

EVACUATE

Move away from danger.

INVACUATE

Move into a safer internal environment when outside may be more dangerous.

LOCKDOWN

Secure people in a protected area and restrict access or movement in response to a serious threat.

The terminology is useful, but the real objective is not knowing three definitions.

It is knowing which protective action may be appropriate for the circumstances facing your organisation.

A final thought

Emergency planning should never be about creating the illusion that an organisation can predict exactly what will happen.

It can’t.

Instead, good planning creates a framework for making sensible decisions when circumstances are uncertain.

For organisations considering their preparedness under Martyn’s Law, evacuation, invacuation and lockdown are therefore worth considering as part of a broader approach to protective security and emergency planning.

The question isn’t simply: “Can we get everyone out?”

It is:

“If something serious happens, what is the safest thing we can realistically ask people to do?”

That is the foundation of proportionate and practical emergency planning.

How Meraxes Secure Ltd can help

At Meraxes Secure Ltd, we help organisations understand their protective-security responsibilities and translate them into practical, proportionate arrangements.

Whether you operate a pub, restaurant, sporting venue, workplace, community facility or another public-facing organisation, effective security does not have to mean turning your premises into a fortress.

It means understanding your risks, identifying sensible measures and being able to demonstrate why the arrangements you have chosen are appropriate.

If you want to discuss your organisation’s protective-security arrangements or Martyn’s Law readiness, get in touch with Meraxes Secure Ltd.

Protecting People. Places. Purpose.

🌐 www.meraxessecure.co.uk