A man with a long gun, an AR-15-style semi-automatic rifle, was shooting people. It was Omar Mateen, 29, an American who had purchased the rifle and a handgun in the past week. He had pledged allegiance to ISIS.

At 2.09am, someone posted a frantic message to Pulse Orlando’s Facebook page: “Everyone get out of pulse and keep running.”

Orlando shooter Omar Mateen was a homophobe and wife beater, reports say

What happened early Sunday morning in Orlando was the latest example of soft-target terrorism, the wholesale slaughter of civilians in locations with minimal security and many potential victims. This one had elements of what happened last fall in Paris - another attack on people having fun at a music venue on a weekend night.

The lucky ones were near an exit or somehow found a way to flee in those first seconds. But the club was designed for congregation, not escapes. Alex Choy, a former club employee, told the Miami Herald that the club has two main rooms, one for performances and drag shows to the left of the front door, and a larger dance room to the right that links to an outdoor patio. “It’s a very, very small space,” he said. “If there was any type of shooting, it wouldn’t take much to get everyone. Very close range.”

Hansen, the club-goer who had mistaken the gunfire for music, said that he escaped through the back of the venue by crawling on his elbows and knees.

“When I got across the street there was blood everywhere,” he said. “I was helping somebody because he was laying down, and I wasn’t sure if he was dead or alive. I took my bandanna off, I shoved it in this hole, the bullet hole that was in his back.

“After everybody was out, the shooting was still going and the cops were still yelling, ‘Go! Go! Clear the area, clear the area!’” he added.

“I was thinking, ‘Are you kidding me?’ ” he said. “So I just dropped down. I just said, ‘Please, please, please, I want to make it out.’ And when I did, I saw people shot. I saw blood. You hope and pray you don’t get shot.”

An officer working at the club exchanged fire with the gunman, authorities said. It was then, according to police, that the incident developed into “a hostage situation.”

Within minutes of the shooting, police vehicles and a SWAT team descended on the club. At the same time, patrons began documenting the horror on their social media accounts. Some were still inside - trapped, but giving real-time updates on the mayhem.

After news of the violence spread, friends and family members began the desperate search for news of their loved ones. Standing outside the dance club early Sunday morning, Mina Justice tsaid she was trying to contact her son, Eddie, and feared the worst.

He had texted her earlier, she said, telling her that he ran into a bathroom with others to hide from the gunman.

“He’s coming,” her son’s text said. That was at 2.39am.

Then the young man wrote: “I’m gonna die.” It was unclear Sunday whether he was one of the casualties.

Someone named Jeff Xcentric Lords posted to his Facebook page that he’d been shot: “losing blood, love u all ...” he wrote. His status, too, remained unclear Sunday.

Tony Torres, another patron, escaped the club, and started shooting video outside. One of his Facebook videos showed at least a dozen police cars, sirens wailing, lights flashing, with a helicopter overhead shining a spotlight on the crime scene. “Get back!” police can be heard shouting. Torres said, “We barely made it out. That is crazy.”

A Snapchat video obtained by WESH-TV recorded more than 20 shots fired in just 9 seconds, while a man said, “Oh my god, people are getting shot, dude” as a woman screamed in the background.

A woman identified as Christine Leinonen raced to the scene at 4am, trying to find her 32-year-old son, Christopher, who she said had been in the club. He remained missing.

“These are nonsensical killings of our children,” she said, sobbing. “They’re killing our babies!”

The nightmare lasted for three full hours, until 5am, when SWAT teams stormed the club. Authorities said 11 police officers and three sheriff’s deputies engaged the gunman in a shootout.

At 5.53am, Orlando Police posted a bulletin: “Pulse Shooting: The shooter inside the club is dead.”

News reports remained sketchy at first as police worked a complicated and potentially dangerous crime scene. They didn’t know how many bodies they were dealing with. About 20, police thought initially. It was much worse than that. By late morning the death toll had risen to 50, with another 53 people wounded, many of them fighting for their lives. Of the dead, 39 had died inside the club, two outside and the rest at hospitals or on the way there.

The bodies lay in the club for much of Sunday while authorities did their investigation and, outside, distraught families waited for news.

Orlando Police Chief John Mina told reporters that even veteran police officers and members of the SWAT team struggled to wrap their minds around the bloodbath. “Just to look into the eyes of our officers told the whole story,” he said. “You could tell that they were all shaken by this incident, by what they saw inside the club.”