Safety Check, part of Facebook’s Crisis Response center, allows Facebook users to mark themselves as safe in times of disaster, or check the statuses of their friends and family. Safety Check is activated after multiple people post about an emergency situation in a given geographic area.
Police say Paddock, who was killed following an encounter with law enforcement, opened fire on the 30,000 attendees of the Route 91 Harvest Music Festival just after 10 p.m. from the 32nd floor of the nearby Mandalay Bay Hotel and Casino.
An associate of Paddock’s, Marilou Danley, is in police custody; it’s unclear if Danley has any connection to the shooting.
The death toll makes the Las Vegas shooting the deadliest such event in modern U.S. history.