Las Vegas Shooting

Yesterday was a horrific night for all of America. A gunman on a high floor of rained a rapid-fire barrage on an outdoor concert festival on Sunday night, leaving at least 59 people dead, injuring 527 others, and sending thousands of terrified survivors fleeing for cover, in one of the deadliest mass shootings in American history.

Online video of the attack near the Mandalay Bay Resort and Casino showed the singer Jason Aldean’s performance at the Route 91 Harvest Festival, a three-day country music event, being interrupted by the sound of gunfire. The music stopped, and as victims fell bleeding, concertgoers screamed, ducked for cover, or ran. “Get down,” one shouted. “Stay down,” screamed another.

Who was the gunman?

Mr. Paddock, 64, of Mesquite, Nev., had no significant prior criminal history, officials said. Investigators are trying to piece together Mr. Paddock’s financial history to search for clues that could help determine what set him off. The F.B.I. has sent dozens of agents and evidence technicians to Las Vegas.

The gunman’s father, Benjamin Patrick Paddock, had a troubled history, according to Eric Paddock of Orlando, Fla., a brother of the suspect. Benjamin Paddock was convicted of serial bank robbery in 1961, according to news reports from the time. After he escaped from prison, he was on the F.B.I.’s “Top 10” most wanted list for much of the 1970s.

Eric Paddock said he had made a statement to the police. In an interview with CBS, he said that his brother was “not an avid gun guy at all,” adding, “if he had have killed my kids, I couldn’t be more dumbfounded.”

“The fact that he had those kind of weapons is just — where the hell did he get automatic weapons?” Eric Paddock asked.

“He has no military background or anything like that,” he added. “He’s a guy who lived in a house in Mesquite and drove down and gambled in Las Vegas.”

He said Stephen Paddock had recently texted him to ask how their mother was faring after Hurricane Irma.

Before dawn on Monday, the police searched Mr. Paddock’s house in Mesquite, a town on the Nevada-Arizona border. The police moved cautiously at first, evacuating surrounding homes in case there were any explosives, but none were found. The Mesquite Police Department said no one was in the house; at least one firearm and ammunition were found, they said, but they gave few other details about what the search turned up.

The police blocked off the entrance to the neighborhood, but Tom Jennings, 76, a forensic engineer, emerged to check his mail. “This is not Mesquite,” he said, wide-eyed and clearly shaken.

“It makes you sick,” he said. “You just never know who you are living next door to.”

Guests at the Mandalay Bay are in shock.

The hotel remained on partial lockdown late Monday morning, as it had since the shooting. The casino floor was largely empty, though a few gamblers played slots. Hotel employees were offering coffee, pastries and cases of water to stranded guests.

A bellman at the hotel said the gunman’s car was still in the valet, which had been shut down.

Melissa Ayala, 41, came to the country music festival with four friends from Orange, Calif. They were drinking and laughing when they heard what they thought was fireworks. She did not realize it was gunfire until a man near them was grazed by a bullet and fell to the ground, blood coming from his neck.

“It seemed like rapid fire,” she said. “There was blood pouring everywhere.”

“Where do you run to?” said her friend, Shami Espinoza, 38, as she wiped away tears.

“It’s either run and get shot and die or stay and get shot and die. Those were the choices.”