A 21-year-old Victoria man celebrating his birthday was among the hundreds injured in what's been called the deadliest mass shooting in modern U.S. history.

Sheldon Mack, son of former CTV Vancouver Island anchor and news director Hudson Mack, was shot twice when a gunman unleashed a hail of bullets from his hotel room down onto a massive crowd at the Route 91 Harvest Festival Sunday night.

At least 59 people including three Canadians were killed in the attack and at least 527 required hospital attention.

Jordan McIldoon, a 23-year-old Maple Ridge man, and Jessica Klymchuk, a 28-year-old Alberta woman, were among the dozens killed in the attack. A third Canadian who has yet to be identified was also killed.

The shooter, 64-year-old Stephen Craig Paddock, was found dead in his hotel room at Mandalay Bay with as many as 16 guns, according to local authorities.

Mack was at the festival celebrating his 21st birthday when shots erupted during country star Jason Aldean's set.

"We thought it was like fireworks or something for the stage, but we heard a few rounds and then we saw people panicking. It all kind of happened so fast," he said from his hospital bed in a Las Vegas ICU, where he underwent surgery for a ruptured colon and broken forearm.

Mack said he was shot in the gut and then nicked again by a bullet and was bleeding badly, so his friend used his belt as a tourniquet until he could get to an ambulance.

One of the other friends he was at the concert with was also grazed by a bullet, while a third friend escaped unharmed, he said.

So much evil in this world, thanking god for watching over me. Sustained 2 gunshot wounds, a ruptured colon, and a broken forearm. — Sheldon Mack (@SMack_era) October 2, 2017

Thankful for those who helped me and prayers out those I couldn't help — Sheldon Mack (@SMack_era) October 2, 2017

"It seems not real, it seems like a nightmare," he said. "I just don't get what drives evil like that or what causes someone to have that in their heart, to just take out innocent people."

Hudson Mack expressed his thanks for the quick-thinking actions of his son's friends and others who pulled him to safety in a heartfelt post on Facebook.

"He helped others last night while the shooting was happening. His friends Liam and Cole helped him and others, and someone saved his life, dragging him to safety and getting him to an ambulance," he wrote on Facebook. "Whoever you are, thank you."

'People were knocking over other people'

Rick Cohen, a Victoria veterinarian, was one of the thousands of people caught in the gunfire.

"There was easily 400 to 500 shots fired," he said. "It sounded a lot initially like the pop that you hear with fireworks and then it became a much more rapid fire."

After the fourth or fifth shot, Cohen grabbed his girlfriend and the two navigated through the swarm of panicked concertgoers trying to flee the attack.

"Anxiety was super high. People were knocking over other people trying to get away," he said. "It was intense. Everybody was panicking, people were screaming and there were a lot of crying, hysterical people. It was a horrific experience."

Victoria Police Chief Del Manak happened to be in the Mandalay Bay hotel complex at the time the attack occurred, but he and his family weren't injured.

"It's so surreal. You see it on TV, and then to literally be in the middle of it at the hotel where the shooter is, it's quite surreal," he told CTV News.

Manak and his wife were at Cirque Du Soleil when the shooting happened about an hour into the show.

"People really didn't know what had happened and most of us kind of thought it was a malfunction in the staging or in the actual performance of the show," he said. But when Manak checked social media, he saw reports of an active shooting. "Within about 15 or 20 minutes of the show stopping and there being a little bit of a gap as to what was actually occurring, there were about eight Las Vegas Metro police officer that came in."

Manak praised the actions of police, who he said reassured patrons and provided clear instructions on what to do: "Get down, stay down and get out of the line of fire."

The crowd of about 3,000 people was under lockdown for about four-and-a-half hours, he said.

"It was tense. I think people were quite nervous. I could hear a couple people were phoning their loved ones and letting them know what the situation was," he said. "I could see a lot of raw emotion coming out. It was very, very surreal to be in that situation."

Flags at half-mast at B.C. parliament

Police weren't speculating on the motive for the attack, which U.S. President Donald Trump called "an act of pure evil."

The FBI said there didn't appear to be an immediate connection to a terrorist organization, despite Islamic State claiming responsibility for the attack.

B.C. Premier John Horgan released a statement Monday condemning the "horrifying" attack and said flags at the parliament buildings would be lowered to half-mast in honour of McIldoon.

"The senseless acts of violence in Las Vegas are horrifying and incomprehensible. Our hearts are with all those affected by last night's shooting," he said. "To Jordan's family, and the family and friends of all those who have lost their lives, we offer our condolences and support.

Friends and relatives of Canadian citizens known to be in the area to contact the Global Affairs Emergency Watch and Response Centre at 1-800-387-3124 or email sos@international.gc.ca.

The federal government’s travel and tourism information branch tweeted information about resources, including a phone number for the Las Vegas Metropolitan Police Department for individuals impacted by the shooting (1-866-535-5654), directions to a family reunification centre, and a warning about diverted flights at McCarran International Airport.

With files from The Associated Press and CTV Vancouver.