As soon as shots started firing around 2:20 a.m. ET, eyewitness accounts began flooding social media, and the club itself alerted party-goers, at about 3 a.m. ET, by posting a frantic message on its Facebook page: "Everyone get out of pulse and keep running."
Hours later, the same post has amassed numerous responses including unconfirmed eyewitness reports of the attack and others trying to locate family members or friends who were thought to be at the club.
One mother, Libia Carmen, who was on the phone with her daughter still allegedly inside the club, posted: "My daughter is in there. Please keep praying for them... She's waiting for cops to be able to come out. I was on the fone and all i hear is shot guns."
Another Facebook user, Ricardo Almodovar, responded: "I was there. Shooter opened fire @ around 2:00am. People on the dance floor and bar got down on the floor and some of us who were near the bar and back exit managed to go out through the outdoor area and just ran. I am safely home and hoping everyone gets home safely as well :( "
Multiple Twitter users, some who were allegedly hiding from the gunman and reaching out for help, described the grisly scene inside. @lakecitymedman wrote "I've never seen so much blood and mayhem or been so scared ever."
At 3:09 a.m., user @briannmolinaa tweeted that he was texting his friend "Emilio who's inside locked up in a closet at Pulse."
The social media community quickly reacted to the terrifying event circulating the hashtag #PrayforOrlando.
The tragedy is now being deemed the deadliest mass shooting in U.S. history.