Gunfire then erupted again and again, in rapid-fire bursts.

Jamey Eller, 66, said she and her friends hit the ground with the first fusillade, and then “the second round came and we started to belly-crawl.” As the shooting continued, they decided they had to get up and run.

“We had no idea where we were going,” she said. “We just kept hearing shooting. It felt like they were following us.”

Image The Las Vegas Metropolitan Police Department released this photo of Marilou Danley, the gunman’s “companion.” Credit... Las Vegas Metropolitan Police Department

Her sister, Cindy McAfee, 56, called her husband, Steve McAfee, who had stayed back in their hotel room — on the 32nd floor of the Mandalay Bay, where the gunman was. “He was looking down and seeing what was going on and said, ‘Just get out of there — he’s not in the venue, he’s here,’ ” Ms. McAfee said. “It was absolutely the most scared I’ve been in my entire life.”

Almost nine minutes after the shooting began, an officer radioed, “We’re still taking gunfire, we’re pinned down.” Seconds later, an officer broadcast: “We need to snuff the shooter before there are more victims. Anybody have eyes on him?”

Some survivors tried to climb the chain-link fence topped with barbed wire around the nearby McCarran International Airport, until firefighters ripped the fence up from the ground, allowing them to crawl under it.

Krystal Legette, who was visiting from New York, was at the Sundance Helicopters office at the airport, waiting for a sightseeing flight around the city, when, she said, three women burst into the building, screaming, “They’re shooting, they’re shooting!” Then another woman came in, bleeding from a bullet wound in her right arm, and Ms. Legette, a nurse, and three others applied a tourniquet.

More and more people ran into the office, until about 100 had taken shelter there, she said. A worker turned out the lights, locked the doors and told everyone to go inside closets and other areas away from the windows.