It was only when the performer on stage dropped his microphone and ran that the true horror of the unfolding massacre dawned on those in the crowd at a country music festival in Las Vegas, many of them Canadian.
Their first thoughts as the sound of automatic gunfire resounded through the area on Sunday, many said, turned to fireworks.
"We heard the shots get fired, we saw the smoke," Ashley Fowler, who was with friends, told the K-Rock radio station in St. John's, N.L. "Everyone thought it was fireworks at the show until Jason Aldean dropped his mic and ran from the stage, so everyone started to run."
As the panic- and fear-stricken crowd of more than 22,000 at the Route 91 Harvest Festival scrambled for their lives, some found themselves running into a wall of people, or an electric fence around the airport. A local with a truck attached a rope to the fence and pulled it down, allowing access to a runway, Fowler said.
"We're all standing on the runway and they literally have to divert any planes landing in Las Vegas to Arizona because we're all standing on the runway running from the shooters," said Fowler, who got separated from her friends in the panic. "I'm in so much shock."
At least 50 people were killed and 400 injured in what's being called the U.S.'s worst mass shooting.
Police said a man opened fire from the 32nd floor of a hotel across from the concert and identified him as Stephen Paddock, 64, of Mesquite, Nev., less than two hours from Las Vegas. SWAT teams using explosives stormed his room in the Mandalay Bay hotel and found he had killed himself, authorities said. He had as many as 10 guns with him, including rifles, they said.
Jody Ansell, of Stonewall, Man., was among the injured. She said in a Facebook message from her hospital bed that she was recovering.
"I was shot in the right arm and the medical staff are taking care of me," Ansell said.
Another Canadian, Monique Dumas of British Columbia, was six rows from the front of the stage when the shooting erupted.
At first she thought a bottle had smashed, and then, like so many others, thought the popping of automatic gunfire was fireworks. The shooting, she said, continued for the minutes it took for her to get out to safety.
Global Affairs Canada did not immediately respond to a request for comment on the number of Canadians who may have been affected by the shooting in the city known for its glitz and gambling.
Prime Minister Justin Trudeau has tweeted out a message of support.
"Words fail this morning. The friendship & support of Canadians is with the victims in Las Vegas & the people of the US."
Las Vegas is a popular tourist destination for Canadians. Visitors from Canada made up nearly half of international tourists who arrived in the city by air last year, according to the Las Vegas Visitor Authority. Residents of Toronto and Vancouver and Calgary account for about one third of all visitors arriving by air.
As she ran for her life, Fowler said she called her father.
"I had to call him, I didn't know what to do," Fowler said. "He was pretty in shock, I was like crying and running and telling him that I don't know if I'll see him again."
Police put up the runway group in a close-by building and then shuttled them by bus into the airport to safety. Fowler said she planned to get some rest at the home of a Las Vegas woman whose daughter was also being held at the airport.
A reporter with APTN decided against attending the Route 91 Harvest Music Festival.
"We are all safe, locked in room at MGM Grand Massive. Shooting at Route 91," Saskatoon-based Larissa Burnouf said in a tweet. "Loud bangs in our hotel lobby security pushed us out."
— With files from the Associated Press.