Orlando Nightclub Shooting Kills 50; Gunman Had Praised ISIS

ORLANDO, Fla.—The deadliest shooting attack in U.S. history killed at least 50 people at a popular gay nightclub here, injured 53, left a community and nation in grief and reignited concern about homegrown American terrorists.

Authorities said Omar S. Mateen opened fire at the Pulse nightclub in downtown Orlando in an onslaught that sent patrons scrambling for the exits. Many remained trapped inside in what became an hourslong siege. During the attack, Mr. Mateen took time to call 911 and claim allegiance to Islamic State, officials said, leading them to treat the shooting as a terror attack inspired by a foreign terror organization.

Police shot and killed Mr. Mateen at about 5 a.m. Sunday, Orlando Police Chief John Mina said. He had carried an assault rifle and a handgun, Mr. Mina said.

“Today we’re dealing with something that we never imagined and is unimaginable,” Orlando Mayor Buddy Dyer said at a news briefing.

Many of the wounded were in critical condition at Orlando Regional Medical Center, where surgeries continued throughout the day, trauma surgeon Michael Cheatham said. Families waited for word of loved ones at an official outpost positioned near the hospital. Later in the day, authorities began releasing names of victims.

Hundreds of people gathered in the glare of flashing red lights on the fringes of the law enforcement cordon around the nightclub, and later at area hospitals, hoping desperately for some word on the fates of their relatives and friends.

More than 12 hours after the attack, anguished relatives paced between Orlando Regional Medical Center and a nearby hotel as they waited for word. They were told that so many were gunned down that victims would be tagged as anonymous until the hospital was able to identify them.

Omar Mateen

“We are here suffering, knowing nothing,” said Baron Serrano, whose brother, Juan Rivera, 36, had been celebrating a friend’s birthday with his husband and was now unaccounted for. “I cannot understand why they can’t tell me anything because my brother is a very well-known person here in Orlando. He is a hairstylist, and everybody knows him.”

A tally of victims whose relatives had been notified began slowly building on a city website; by 3:30 a.m. on Monday, it had 18 names. Among them was Juan Ramon Guerrero, a 22-year-old man of Dominican descent who had gone to the club with his boyfriend, Christopher Leinonen, who goes by the name Drew, because they wanted to listen to salsa. A friend, Brandon Wolf, watched people carry Mr. Guerrero outside, his body riddled with gunshot wounds.

But no one knew what had become of Mr. Leinonen. His mother, Christine, anxious because of health problems, had woken at 3 a.m. to news of the shooting, and learned from Mr. Wolf that her son had been inside.

A three-hour standoff followed the initial assault, with people inside effectively held hostage until around 5 a.m., when law enforcement officials led by a SWAT team raided the club, using an armored vehicle and explosives designed to disorient and distract. Over a dozen police officers and sheriff’s deputies engaged in a shootout with Mr. Mateen, leaving him dead and an officer wounded, his life saved by a Kevlar helmet that deflected a bullet.