News was continuing to unfold quickly about attacks in Paris that killed dozens of people Friday evening, and the death toll was rising.

As it has during past emergencies, Facebook is asking those nearby the chaos to check in as "safe." Those with loved ones in or around Paris can use the resource to see whether their friends or family are OK and have reported in.

The tool was introduced last year and widely used during the April Nepal earthquake.

In addition, those concerned about U.S. citizens in Paris can call 1-888-407-4747 (from the US) or 202-501-4444 (from overseas) for assistance, the U.S. State Department said.