Las Vegas resident Angela Mendoza woke up to missed calls and texts asking her if she was okay. She responded to her friends and family, then checked the news and social media—which led her to post an offer of transportation for people in need.

"I think since we're so tied in on social media now, it's one of the first places you check for updates on your connections or any details the news might've missed," she said via Facebook Messenger.

Mendoza is just one of many people who turned to Facebook in the aftermath of the worst mass shooting in U.S. history. A gunman opened fire from a hotel room, killing at least 50 people and injuring more than 400 people at a nearby concert. Mendoza said Reddit and Facebook became her go to for information—particularly on people close to her who might have been hurt.

"I checked Reddit and Facebook right after checking news updates because they have the details from people who were there and you check and pray you don't have family and friends who have been affected," Mendoza said.

On Facebook, Mendoza marked herself safe on the Safety Check feature, then posted an offer of free transportation for three people. Dozens of people have posted offers of shelter, food, transportation, and other forms to Safety Check as of Monday morning.

The central role played by Facebook in peoples' lives is never more apparent than during a crisis. No other social platform has ever approached the totality of its network, making it a near-complete tally of a person's life and what is relevant to them. For all of Facebook's faults, there's no other website that can claim to provide that kind of utility.

TaNesha Haley, who posted an offering of homemade food for 20 people, said that Facebook provided crucial information, particularly about people in her life.

"I could not find any information anywhere else about people that were safe or any place that I can help with those items listed," she said in a Facebook Messenger interview.

Haley said she want to the local FOX 5 news affiliate Facebook page on Sunday evening after hearing about the shooting. Her News Feed quickly filled up with updates about the situation, leading her to start making food. She was tagged on Safety Check by her friend, which led her to see the growing number of people offering help.

Las Vegas resident Randy Dorfman posted to offer shelter and transportation for six people. Dorfman said he had marked himself safe, at which time Facebook prompted to ask if he would like to provide assistance.

Dorfman said it wasn't just about helping neighbors, but that he also figured there would be people from out of town with few options.

"I'm sure many of the victims are not from Vegas, so we have large home and can provide food, shelter and transportation for those in need," Dorfman said in a Facebook Messenger conversation.

Judi Hurd had the same reaction. She saw that a friend had marked herself safe. Hurd did the same and was then prompted to help. "If anyone in Vegas needs a ride, food, water, child care while donating blood, anything...PM me," she posted.

Facebook's Safety Check is among the best examples of the good and the bad that can come from the social network in times of crisis. Around the fire that destroyed a London apartment block and killed more than a dozen people, Safety Check became a controversial tool for providing more confusion and noise than anything else.

In the wake of the shooting in Las Vegas, Safety Check provided a way for people to find shelter, but also promoted misinformation.

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This is the yin and yang of Facebook. The social network has made numerous efforts to become a force within politics, particularly for local communities, but it's also in the midst of its most serious scandal yet over how Russia may have used its platform to spread propaganda and misinformation in the run up to the 2016 election. Facebook has responded with CEO Mark Zuckerberg publicly discussing what happened and vowing to make changes.

At the same time, Facebook has pushed to make Groups a bigger part of its purpose in hopes of getting Facebook users more active around interests and shared experiences rather than just passive consumers. Facebook has also embraced its role as an important hub in times of crisis, launching Community Help and Crisis Response tools that go beyond just marking people as safe. Those efforts haven't always been perfect, but they've been important in cementing Facebook's role as the go-to platform for people to connect with loved ones and figure out how to help.

Even casual Facebook users see the value. Taren Charles said she doesn't check Facebook much but went to it after hearing the news. She marked herself safe on Safety Check, then downloaded Facebook Messenger to talk with people in need of help.

"I was worried about a lot of people and Facebook provided a way to connect with them and make sure they're okay," Charles said. "To be honest, I received the most amount of information from [televised] news, but Facebook was very useful as well today.

These kinds of efforts by Facebook haven’t been perfect. Sometimes, they sow discord and hysteria in chaotic moments when it’s already in abundant supply. But they've also been crucial components in cementing Facebook as the go-to platform for people trying to connect with loved ones (and then, figuring out how to help) during those same times.

Another way to put it: In the harsh light of day, mere hours after a tragedy that’ll have those whose lives it touched reeling for years to come, it’s hard to look at most of the people using Safety Check in Las Vegas this week, and see a net-negative. Even if nothing comes of their offers for help, at the very least, Facebook has demonstrated that it can still be a place for people to come together, and express altruistic ideals, if not maybe get people acting on a few of them, too.

It’s a feature that’s easy to overlook, except by those whose lives it touches in their most difficult moments—when it becomes the kind of innovation we never needed, until we suddenly don’t know where we’d be without it.