Invacuation: what it means and how it differs from lockdown

What invacuation means

Invacuation means moving people away from danger to a place where they are less likely to be harmed. That can mean bringing people in from outside, or moving them within the building to a safer area. The statutory guidance for the Terrorism (Protection of Premises) Act 2025, known as Martyn's Law, lists it as one of four public protection procedures, alongside evacuation, lockdown and communication.

It is the opposite of an evacuation. In an evacuation the safest place is outside; in an invacuation the safest place is inside.

When to invacuate

Invacuate when the threat is outside and the building offers protection. Examples:

an incident in the street, on a neighbouring site or close to the school gates;
a suspicious item or a person acting suspiciously near the entrance;
smoke or a chemical release nearby, where staying inside with windows shut is safer;
a dangerous dog or an aggressive person on the playing field.

If the danger then comes closer, an invacuation often becomes a lockdown: once everyone is in, the doors are secured.

Invacuation, lockdown and evacuation compared

	Invacuation	Lockdown	Evacuation
Where people go	Inside, to a safer area	Stay inside, in secured rooms	Out of the building, dispersing
Doors	Open to let people in, then closed	Locked, nobody in or out	Open to let people out
Typical threat	Outside	On site or at the door	Inside

The steps in an invacuation procedure

Raise the alert with a signal everyone recognises as invacuation, distinct from the fire alarm and from lockdown.
Bring people inside by the nearest safe entrance, away from the direction of the threat.
Close and secure outside doors and shutters once everyone is in.
Move to safer areas: the statutory guidance suggests areas at a distance from windows, exterior walls and entry points (7.40).
Account for everyone with registers, including visitors and contractors.
Wait for instructions and the all clear, ready to move to lockdown or evacuation if things change.

Invacuation in schools

The hardest moment for a school is break time or lunchtime, when hundreds of pupils are outside. Plan which entrances each year group uses, who holds the doors, and who sweeps the playground, field and toilets. Practise it at break, not only in lesson time. Tell parents what invacuation is before the first drill, and use calm, simple language with younger children.

Telling everyone at once

Invacuation depends on everyone hearing the instruction at the same moment, inside and out. A whistle or handbell outside, the PA inside, and an alert on every computer and screen reach different people. Lockdown Alert puts your alert on every PC and screen at the site within seconds, from a phone call, a panic button, an email or the portal. The words on the screen are set per site, so they can say exactly what staff should do.

Questions people ask

What does invacuation mean?

Invacuation means moving people away from danger to a safer place, by bringing them inside or moving them within a building. It is used when the threat is outside and the building gives better protection than leaving it.

What is the difference between invacuation and lockdown?

Invacuation brings people inside, or to a safer part of the building. Lockdown secures the building so nobody can get in or out. An invacuation often comes first, and the site then locks down once everyone is inside.

What is the difference between invacuation and evacuation?

They are opposites. Evacuation moves people out of a building because the danger is inside. Invacuation moves people in because the danger is outside.

Is invacuation part of Martyn's Law?

Yes. The Terrorism (Protection of Premises) Act 2025 lists four public protection procedures: evacuation, invacuation, lockdown and communication. Premises in scope must have appropriate procedures in place, so far as is reasonably practicable, from the start of the duties, expected in spring 2027.

Where should people go during an invacuation?

To areas inside the building away from windows, exterior walls and entry points, as the statutory guidance suggests. Pick these in advance for each part of the site and include them in your plan.

Sources

Terrorism (Protection of Premises) Act 2025: statutory guidance (Home Office)
Evacuation, invacuation, lockdown, protected spaces (ProtectUK)
Protective security and preparedness for education settings (DfE, PDF)
Terrorism (Protection of Premises) Act 2025 (legislation.gov.uk)

This page is general information, not legal or security advice. Your own risk assessment and local police advice come first.