(ORLANDO, Fla.) -- Eyewitnesses described a scene of complete chaos with "blood everywhere" in the three horrific hours between when an armed gunman opened fire inside an Orlando, Florida gay nightclub and when a SWAT team entered the building, rescued the hostages the gunman had taken, and then killed him.
One eyewitness who was released from the hospital Sunday night told ABC News he played dead for three hours as the gunman, who authorities have identified as 29-year-old Omar Mateen, walked around, talking to club patrons still inside. Then, the witness said, he heard the shooter on the phone saying, "Stop killing ISIS" and "I've got plenty of bullets."
By the time the attack was over, at least 50 people had been killed and at least 53 were injured.
At 2 a.m. Sunday morning, there were about 320 people at the Pulse nightclub, officials said.
At 2:02 a.m., bartenders announced last call, then, law enforcement officials said, Mateen, armed with an assault rifle, a handgun and multiple rounds of ammunition, walked in.
"The music was playing, everyone was dancing ... and that's where you heard the 'Bang, Bang,'" said Javier Antonetti, who was inside the club at the time. "The one guy next to me fell and there was blood everywhere."
A uniformed off-duty police officer working security at the club responded. He and two other officers exchanged gunfire with the suspect, according to officials.
"Our officer engaged in a gun battle with that suspect," Orlando Police Department Chief John Mina said. "The suspect at some point went back inside the club, more shots were fired."
The club has three main areas -- the Hip-Hop Room, the main bar with the dance floor and a patio area. Some club patrons tried to take cover and others escaped out a side door and into an alley.
"We are literally trying to hide underneath the bar," said Janiel Gonzalez, another eyewitness. "People are screaming, they are crawling on the floor... I just remember telling myself, 'This is not how I die.' Like, 'Not today, it's not today,' and, 'not like this at least.'"
Both Antonetti and Gonzalez said they dropped to the floor and tried to crawl to the nearest exit amidst the chaos.
"All I know is to just get out, so when I dropped I crawled out," Antonetti said. "And I was crawling, I just kept crawling."
"It was complete mayhem," Gonzalez added. "Everybody was just so, so nervous and we wanted to get out, people were getting trampled. We were just trying to push everybody out the door."
By 2:09 a.m., the nightclub posted a chilling warning on its Facebook page, saying, "Everyone get out of pulse and keep running."
When he got outside, Gonzalez said he could see people covered in blood. Antonetti said there were "bodies everywhere."
"In the parking lot they were tagging them red, yellow, so that they know who to help first and who not to help first," Antonetti continued. "There was pants down, shirts cut off, they had to find bullets. There was just blood everywhere."
People continued to try to escape, but dozens were stuck and became hostages, law enforcement officials said at a news conference earlier Sunday. After the shooting began, Mateen, a U.S.-born citizen with Afghani parents who lived in St. Lucie County, Florida, called 911 to pledge his allegiance to the terror group ISIS, officials said.
Armored vehicles and a SWAT team rushed to the scene, but then waited outside the club for nearly three hours.
"In that time we need to set up, reevaluate, reassess what's happening and make sure that all the pieces were in place," Florida Department of Law Enforcement supervisor agent Danny Banks said at a news conference.
At approximately 5 a.m., the SWAT team made the decision to rescue the hostages, officials said. Police set off controlled explosions inside the club to distract the gunman. An armored vehicle smashed through a wall of the club and officials swarmed in behind. Eleven Orlando Police officers exchanged gunfire with the shooter, according to Mina.
"We made a decision to do an explosive entry on the outside of the club to get to those people, and our SWAT team at that time encountered the suspect somewhere in that area near one of the doorway entrances and shot and killed him," Mina said.
Then at 5:53 a.m. Orlando police tweeted, "The shooter inside the nightclub is dead," referring to Pulse Nightclub, which bills itself on its website as "Orlando's Premier Gay Night Club."
The massacre at the Pulse nightclub early Sunday morning has been described as a "domestic terror incident," and the worst mass shooting in U.S. history and the deadliest terror attack on U.S. soil since the events of Sept. 11, 2001.
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