Facebook's Safety Check feature was activated Monday in the wake of an explosion at a concert in Manchester, England, that killed 19 and injured about 50 more.
The explosion occurred at the conclusion of an Ariana Grande concert at the Manchester Arena just before 10:35 p.m. local time. Greater Manchester police said it was "currently being treated as a terrorist incident until police know otherwise."
Many of the victims were young girls, a US law enforcement source who received a preliminary briefing told CBS News. The source said two explosions occurred, both involving nails.
Safety Check sends a message to Facebook users in areas of immediate danger, allowing people to notify friends and family that they are alive and well. It has been used for natural disasters like hurricanes, as well as mass shootings and terrorist attacks.
The Facebook tool has been activated more than 300 times in the past three years, but it has also been criticized for failing to activate Safety Check in some parts of the world. In response, the social media giant no longer manually activates the tool, relying instead on user activity to automatically trigger alerts, tracking keywords indicating danger like "earthquake," "shooting" or "explosion" in concentrated areas.
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