Facebook has activated its Safety Check feature to let users mark themselves as safe
Facebook has activated its Safety Check tool following the London terror attack in Westminster this afternoon.
The tool lets Facebook users in the area near the attack mark themselves as "Safe", allowing friends and family to quickly search for and find out if anyone they know has been affected.
The attack has left five people dead so far, including the terrorist and one police officer.
London Terror Attack: Latest Pictures Thu, March 23, 2017
4 dead and 40 injured in Westminster terror attack
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Security services staff pick through debris, including a car number plate, left following the March 22 terror attack on Westminster Bridge in central London
Facebook users can mark themselves safe using a dedicated page for the London terror attack, or indicate that they are not in the affected area.
They can also send an alert to their Facebook contacts in order to check that they are OK.
First launched in 2014, Safety Check was started by Facebook to help the victims of natural disasters, and was initially used to help the recovery of victims from earthquakes in Japan, Chile and Nepal.
Today's action marks the first time that the feature has been used in the UK.
Facebook Safety Check lets you mark yourself as safe
Facebook also turned on Safety Check following the terrorist attacks in Paris last October in which 130 people died, allowing those caught up in the tragedy to let their loved ones know they were safe.
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And it was also activated after the attacks on Brussels airport in March which left 32 people dead, and the Orlando shooting in Florida last June.
The company had been criticised for its apparent refusal to use Safety Check for a number of major incidents, but a Facebook spokesperson said that it could soon be able to allow individual users to turn on the feature themselves.