UPDATED 6 p.m. PT
Facebook activated its "safety check" feature in the wake of the terror attacks in Paris on Friday.
The feature, which has previously been used in natural disasters, allows people in the affected areas to let Facebook friends know they are safe. Hundreds of millions of Facebook users saw notifications about their friends in Paris in the hours after Friday's attacks, according to the company.
Safety check was used by more than 4 million Facebook users in Paris during the first 24 hours following the attacks, a Facebook representative told Mashable Saturday evening. And 360 million people around the world received notifications that their friends were safe.
Users can also visit the safety check website to see which of their friends are in the area and who has checked in as safe.
The feature sends push notifications to Facebook users who have friends in the affected area, alerting them when friends have marked themselves as safe.
Grateful for Facebook's safety check feature for Paris tonight. pic.twitter.com/iDJ7dRCroy— Jeff Jarvis (@jeffjarvis) November 14, 2015
Facebook introduced the feature last year and CEO Mark Zuckerberg said it was inspired by the devastating earthquake that hit Japan in 2011.
Many on social media applauded the feature on Friday evening.
HUGE #kudos to @Facebook for this life-saving, and incredibly useful feature for friends & family caught in-crisis pic.twitter.com/OaQa7IGdDH— Jamie Kerr (@HootJamie) November 14, 2015
Some of my friends and colleagues have marked themselves safe on Facebook. Useful feature in case people can't contact family and friends.— Heba Fawzy El-Masry (@HebaFawzy83) November 14, 2015
Facebook Safety Check sending me notifications about my friends in Paris. Useful tool. pic.twitter.com/YF8aNYOGkL— Katie Khan (@katie_khan) November 14, 2015
The social network previously activated the feature following the April 2015 earthquake in Nepal and earlier this year during Hurricane Patricia, which hit Mexico in October.
Updated November 14, 2015 at 6:03 p.m. PT with stats from Facebook.