Many had already been shot as authorities surrounded Orlando's Pulse nightclub, where the wounded tried to hide from the gunman as they used their phones to make desperate pleas for help.
"He's still in the bathroom and is bleeding, he got shot," one man told a dispatcher about his son, crying on the phone. "Nobody is going in for him."
The emotional call was one of multiple 911 calls released Tuesday by the Orange County Sheriff's Office of the June 12 attack, where 49 people were killed and another 53 were injured in the worst mass shooting in modern US history.
"We have lots of help out there," the dispatcher told the father, assuring him that officials had surrounded the club and were preparing to go inside. "They're trying to get to him."
Emergency dispatchers in Florida were flooded with frantic 911 calls from witnesses and family members as shots rang out during the massacre.
The recordings provide a window into how family members desperately tried to get help to loved ones trapped inside the club, while dispatchers tried to get details about conditions inside.
Some of the calls came from neighbors and nearby businesses who heard the barrage of gunfire from the nightclub. Others came from friends and relatives who began to receive text messages from people asking for help as the gunman, Omar Mateen, continued the assault.
One caller told dispatchers his girlfriend was trapped inside with more than a dozen people in a bathroom. Some were bleeding badly.
"They're all scared to death and they think they're going to die," he told the dispatcher.
With little to go on, dispatchers also tried to get information about the gunman and the wounded inside.
They asked the caller if his girlfriend texted him any information about the gunman, or where in the club he might be.
"All she's texting me is 'The shooter is there, the shooter is there,'" he said.
Minutes later, the man called back, growing frustrated as his girlfriend, still trapped, continued to text him updates.
"There are now four dead in the bathroom and two shot are bleeding out," he told a dispatcher, asking for help for his girlfriend hiding in one of the club's bathrooms. "If someone doesn't get there soon, they're going to die."
One woman told dispatchers her son was hiding inside the bathroom of the club. Another woman nearby said stray bullets were hitting the walls and door of her building.
One caller told dispatchers he had just walked out of the club when the firing started.
"We were leaving the club and as soon as we left, gunshots were going like crazy," he said.
Another woman called police from her home while her son was on the other line.
"My son is stuck in the bathroom down there, and I got him on the other line," she told the dispatcher.
"What I need him to do is just stay where he is," a police dispatcher told her.
While the Orlando Police Department was the main agency in charge of the incident, 911 calls began to overflow to the sheriff's office as people heard the barrage of gunfire around 2 a.m.
One man who lived near the club called police when he said someone was knocking on his door.
Confused and scared, the man told a dispatcher in Spanish he had no weapons, and he believed someone was attacking the nightclub. The dispatcher told him deputies and officers were responding to an active shooter at Pulse.
Mateen was killed after authorities stormed the nightclub.
The Orlando Sentinel reported that Orlando Police had declined to release the 911 calls their department received during the shooting, arguing that they were exempted from public disclosure.
Multiple media organizations, including the Orlando Sentinel and the Associated Press, have sued the agency for the recordings.