When hurricane Sandy made landfall, phone lines went busy or dead and for those who could make calls, the 911 hotline was frighteningly backed up.
But for many stuck in the throes of the storm, social media like Twitter and Instagram became stranger-to-stranger lifelines.
>> Home-bound Instagram users logged photos of trees blocking the entrances to their driveways.
>> "Please help! My parents trapped in ManhattanBeach-Exeter Street bet Sheepshead Bay/Hampton Ave.," tweeted Sandi DuBowski of Brooklyn. "Water overtaking house they need rescue."
DuBowski's 140-character message, in fact, was tweeted and retweeted as he waited for hours for emergency services to arrive to aid his parents.
He pleaded repeatedly with the New York Fire Department Twitter account, reading messages of support from other users as he waited.
Finally, it paid off.
"Great news! Neighbor called," he tweeted hours later. "I spoke to Mom b4 phone cut off. She/Dad alive, I think OK but not sure. First contact. Joy, relief!"
Similar stories trickled out as good samaritans offered advice about crisis situations, and social media became a way to update friends and followers on their status.
Laura Damelio posted a picture of fallen trees cutting off her driveway and tagged it with a series of hashtags: "Officially trapped on the nect #tree #down #hurricane #sandy #mallard #drive #hellp #SOS
On Twitter, Manhattan-based literary blogger Ron Hogan made an urgent plea to his followers for a portable generator for a friend who needed to power a ventilator.
"If anybody with a portable generator can get to lower Manhattan, contact @lizhenry -- she has a friend on a ventilator who needs your help," he tweeted.
Before the firefighters arrived to help, Hogan was inundated with replies warning him of the dangers of generators and offering to friends in the emergency medical services to fast-track his case.
"No power and no way out of the neighborhood," tweeted Kelly McCaffrey, a student in Baltimore. "Trapped indefinitely. At least we have the generator running. About 28 hrs left of fuel."
For some, Twitter served as a search engine for who-to-contact in which-disaster situation.
@gracecunning Who do I call for a tree on my house/porch!?!?! Seriously. Everyone's ok, tree on porch
Others just vented or updated their followers on their current location.
Gabe Kahn, a professor of journalism and media at the USC Annenberg Innovation, said Twitter has again proven itself as a reliable tool for criss communication.
"Twitter is great and people have used Twitter very expertly in floods in Australia and when they were snowbound in Manhattan," he told TheWrap.
He said social networks connect users with emergency services and journalists.
"Ordinary citizens post information and share out, and draw information from an app so that I can see if there is a fire coming my way or the intersection is blocked," he said, adding that emergency responders can sift through the deluge of 911 calls by cross referencing the calls with tweets and posts online, which also educate news reporters as they put out stories.
"It allows people to ask for help and offer help on this platform," he said. "If you post a photo of your car getting stuck in a sink-hole, someone nearby might say 'Oh, I have a Jeep with a wench -- no need for emergency services."
Rebecca Rosenberg and Colin Sylvester contributed to this report.