A Facebook page designed to let users check on the safety of friends and family during a crisis also showed graphic videos of the Las Vegas massacre, showing the challenge the company faces in keeping unwanted content off its site while also protecting users' freedom of speech.
Some of the videos — posted by individual Facebook users and a broad range of national media organizations, including CNN, ABC News, NBC News and the Washington Post — included warnings that they contained graphic or disturbing images.
Facebook created its Safety Check service in 2014 to give users a way to communicate their status to loved ones in the wake of a natural disaster, mass shooting or other deadly event.
Yet early Monday, a section of the page devoted to the mass shooting in Las Vegas contained posts showing bloody bodies lying in a parking lot and scenes of panic as concertgoers tried to flee to safety while a gunman opened fire from a nearby hotel.
The video content on what is now the deadliest mass shooting in U.S. history adds to evidence that the company may be on a collision course with those who say it must do more to keep such content off its site.
Facebook already faces growing pressure in Congress for a full accounting of political ads bought by Russian groups trying to influence the 2016 U.S. election.
The company said last month it would turn the ads over to Congress and increase transparency of all political ads.
On Monday, Facebook said it had done so and also would hire an additional 1,000 workers to police ads on its site.
In Europe, meanwhile, the company faces tougher new laws, after leaders accused it of helping terrorists by hosting recruiting and propaganda videos.
Facebook CEO Mark Zuckerberg has made clear that while the company is committed to doing more to prevent the use of the site for nefarious purposes, it is unable to prevent all such instances of disturbing or misleading content.
In a Sept. 21 post, Zuckerberg also questioned whether stopping every piece of content from appearing on Facebook is compatible with protections enshrined in the U.S. Constitution's First Amendment:
"Now, I'm not going to sit here and tell you we're going to catch all bad content in our system. We don't check what people say before they say it, and frankly, I don't think our society should want us to. Freedom means you don't have to ask permission first, and that by default you can say what you want."