Facebook activated Safety Check in London on Wednesday afternoon following a suspected terrorist incident at the Houses of Parliament in Westminster.
The Met Police were called to Westminster Bridge at 2:40 p.m. after a car crashed into railings and gunshots were heard outside Parliament. "We're treating this as a terrorist incident until we know otherwise," the Met said in a statement.
Four people have died, including a police officer, and at least 20 people are injured. London Ambulance Service said it had treated 10 people on Westminster Bridge. The area around the Houses of Parliament has been placed on lockdown, and a number of tube stations in the surrounding area have been closed. Meanwhile, Facebook has invited Londoners to mark themselves as safe online.
Safety Check, introduced in October 2014, allows people to let friends and family know they're safe following a disaster or other incident. The last time Safety Check was activated in London was during a tram crash in Croydon in 2016.
In the wake of the Westminster incident, news organizations posted images on Twitter in which victims were identifiable. Police encouraged people to "use common sense and restraint in circulating pictures and videos of those that have been injured."