Desperate for help and unsure whether traditional rescue efforts will come through, Harvey victims are using social media to share maps of their location and photos of themselves trapped on rooftops and inside buildings.

“Need help in NE Houston! Baby here and sick elderly!” one user posted on Twitter along with her address late Sunday.

Another woman, Alondra Molina, posted Monday on Facebook that her sister was desperate for a rescue for herself and her four children, including a 1-year-old.

“Please if someone could at least get them out of the city me and my mom will come get them,” Molina wrote on a Facebook group where dozens were pleading for help. “The roads are just all blocked and we can’t get in.”

Annette Fuller took a video when she began fearing for her life Sunday. She was on the second floor of a neighbor’s home along with the residents of three other houses as water rose and hit waist level on the first floor.

“We called 911, and it rang and rang and rang and rang,” Fuller said Monday after the water receded and she managed to return safely to her single-story home.

“There’s just no agency in the world that could handle Harvey,” she said. “However, none of us were warned that 911 might not work. It was very frightening.”

Fuller’s two daughters, who live in Austin and Dallas, posted her video to Facebook after their mother texted it to them, and the post went viral.

A nursing home in Dickinson, a low-lying city 30 miles southeast of Houston, quickly became the face of the crisis after its owner took a photo of residents , some in wheelchairs, up to their chests in water.

The nursing home owner, Trudy Lampson, sent the photo to her daughter, whose husband posted it Sunday to Twitter, where it’s been re-tweeted about 4,500 times.

The photo was so dramatic that many users denounced it as fake. The nursing home residents were saved the same day.

“Thanks to all the true believers that re-tweeted and got the news organizations involved,” Lampson’s son-in-law, Timothy McIntosh, posted later in the day. “It pushed La Vita Bella to #1 on the priority list.”

McIntosh said Monday that his post gained traction after a local newspaper reported it.

“We are in Tampa, Florida,” he said. “The only way we could have an impact was by trying to reach out to emergency services and trying to do social media to gain attention to the cause.”

More than any other natural disaster, Harvey has made it clear that social media has revolutionized the search-and-rescue process, said Karen North, a professor of social media at the University of Southern California.

“And what’s really fascinating is that this is not emergency services experts creating strategic systems to rescue people,” North said. “This is evolving organically. … Not only can people reach out to 911, but to friends and family elsewhere who can not only reach out to 911, but directly to rescuers in the location where the person needs help.”

Fuller said if the water rises again at her home, she won’t bother calling 911 and will post directly to social media.

“If I was desperate, I’d put it in a public Facebook site and say, ‘Somebody please help,’ and hope that somebody was looking,’” she said.