Distraught family members waited to hear about their loved ones as officials began identifying victims from Sunday's early-morning massacre at an Orlando gay nightclub — the deadliest mass shooting in U.S. history.
By sunrise, at least 50 people were dead and 53 more were hurt.
Witnesses described terror-filled moments.
A DJ hid behind his booth. Loved ones got separated from each other as they sprinted away from the club so fast their shoes fell off. People carried bloodied strangers, suffering from gunshot wounds, to ambulances waiting nearby.
The gunfire, which erupted about 2 a.m. at Pulse nightclub, lasted for the duration of one song, a witness said.
The gunman, who was killed in a shootout with police about 5 a.m., was identified by theFBI as Omar Mateen of St. Lucie County. The agency interviewed Mateen, 29, three times in 2013 and 2014 for expressing ties to terrorist organizations and contacting a suicide bomber, but they determined he wasn't a threat.
"This is probably the most difficult day in the history of Orlando," Orlando Mayor Buddy Dyer said Sunday.
Officials worked to identify the dead, but by early Monday they had only released 15 names, with the victims ranging in age from 20 to 50. They warned the process would take time.
As hours elapsed after Sunday's shooting, Orlando and Orange County remained under a state of emergency at the order of Dyer and Florida Gov. Rick Scott.
'I saw fire coming out of his gun'
More than 200 people went to Pulse at 1912 Orange Ave., south of downtown Orlando, to celebrate Latino Night.
The first shots sounded about 2 a.m. as Mateen exchanged gunfire with an Orlando police officer. Mateen, armed with an assault rifle and a pistol, then ran further inside the club and started shooting into the crowd.
Witnesses said Mateen aimed at people, who dropped to the ground. For the next three hours, law enforcement and SWAT members worked to rescue hostages from inside the club.
"People were trampling over each other," said Jillian Amador, whose arm was cut by broken glass. "I feel terrible. I have anxiety. I'm scared. I don't want to go out."
"At first I thought it was fireworks ... I didn't believe it, then I saw people on the ground and people running," she said.
About 5 a.m., police and SWAT members put an explosive device on a wall of the club and plowed through it with a battering ram. That's when Mateen rushed toward them and opened fire in his final, fatal gun battle.
Rosie Feba was there with her girlfriend.
"She told me someone was shooting. Everyone was getting on the floor," Feba said. "I told her I didn't think it was real, I thought it was just part of the music until I saw fire coming out of his gun."
Many worried relatives looking for loved ones Sunday flocked to makeshift headquarters set up by Orlando Regional Medical Center at a nearby hotel.
Maria Arocho of Orlando anxiously awaited information about her cousin Martin Torres.
"It's just so nerve-racking," Arocho said. "I haven't heard from him. What do I do? We call him and it goes straight to voice mail."
Others rushed to donate blood — specifically types O-negative, O-positive and AB plasma that were in short supply — at such a rate that centers asked donors to return later in the week when banks need to be replenished.
Victims experiencing emotional trauma related to the shooting can dial 2-1-1 for support, said Ashley Blasewitz of the Heart of Florida United Way.
By Sunday night, dozens of vigils were held across Central Florida and the nation, including a vigil in Newtown, Conn., where 27 people died in a 2012 mass shooting.
As more details of Orlando's tragedy unfolded, President Barack Obama tried to console a grieving nation after the deadliest mass shooting since Virginia Tech in 2007, in which 32 people and the shooter died.
The terrorist attack, Obama said in a televised news conference, reminds the country how easily someone can purchase a weapon that fires into a movie theater or house of worship.
Obama specifically offered condolences to lesbian, gay, bisexual or transgender Americans who frequent Pulse and other clubs like it across the country.
"The place where they were attacked is more than a nightclub — it is a place of solidarity and empowerment where people have come together to raise awareness, to speak their minds and to advocate for their civil rights," he said.
Locally, LGBT and religious groups are rallying together in the wake of the shooting, condemning Mateen's actions.
"There is never, ever any justification for such unacceptable crimes against humanity, crimes against God, crimes against our country," said Hassan Shibly, executive director of the Florida branch of the Council on American-Islamic Relations.
His statement was one of several offered by local Islamic groups. Imam Muhammad Musri, president of the Islamic Society of Central Florida, urged people to pray on what he called "a heart-breaking morning."
At a midday news conference, Carlos Guillermo Smith, a representative of Equality Florida, an LGBT advocacy group, stood beside Shibly.
Smith reiterated that the two communities are united.
"Let me be clear: Equality Florida stands in solidarity with the Muslim and Islamic community and in opposition to the intolerance, discrimination and hate crimes that both of our communities experience," Smith said.
Staff members Naseem Miller, Josh Robbins, David Harris, Bethany Rodgers, Rene Stutzman, Gal Tziperman Lotan and Bob Drogin contributed to this report.