US & CANADA : Over 50 dead, 200 injured in Las Vegas after deadliest shooting in modern US history

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More than 50 people were killed and 200 injured when a lone gunman opened fire from a perch high up in the Mandalay Bay Resort and Casino in Las Vegas Sunday night, police said, making it the deadlest shooting in modern U.S. history.

The “nonstop gunfire,” according to one witness, sent bystanders outside the resort on the Vegas strip ducking for cover and scrambling for their lives. Tourists hid in their hotel rooms and flights headed into the McCarran International Airport were held elsewhere.

Bystanders sprang into action, caring for the wounded and at least one described someone dying in their arms.

Police said a Las Vegas police officer who was off-duty attending the concert is among the dead.

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One video showed the terrifying aftermath as the injured lay on stretchers or on the ground with responders and bystanders surrounding them to give aid. Bystanders made makeshift stretchers out of police barricades, plugged wounds with their hands and used their clothing to try to stanch the bleeding from the wounded.

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Videos filmed by onlookers gave a window into the chaos that ensued, with some thinking that fireworks were going off. The final night of the Route 91 Harvest Music Festivalwas taking place across the street from Mandalay Bay. Jason Aldean was the night’s headliner; other performers included country stars Jake Owen, Big & Rich, Luke Combs and Dylan Scott.

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In the wake of the shooting, the Las Vegas Police Department said the suspected gunman, who was believed to be a local resident, was on 32nd floor of Mandalay Bay hotel. Police responded to the scene, engaged him and he is now dead. Law enforcement officials identified the suspect as 64-year-old Stephen Paddock.

Authorities were looking for a companion of the shooter, Marilou Danley, and authorities later said this morning, “We’re confident — but not 100 percent sure — we have located the female person of interest.”

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“We were just at the concert there, and Jason Aldean was playing,” one of the concertgoers, named Mike Cronk, 48, a retired teacher, told ABC News. “Kind of sounded like some fireworks going off. I think there was the first kind of volley, and then all of the sudden second volley. My buddy’s like, ‘I just got hit, you know.’ He got hit three times. Then people started diving for the ground. And it just continued.

“It was pretty much chaotic,” Cronk continued. “Lots of people got hit. … It took a while to get him out. We had to get him over the fence and hiding under the stage for a while, you know, to be safe. And, finally, we had to move him because he had three chest wounds.”

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Cronk said his group were finally able to track down an ambulance “and basically the one guy ended up dying in my arms because he was bleeding,” he said. “And my buddy got in there. We got three more people in the ambulance. … But I just got a message from my buddy — and he’s going to be okay.”

As bursts of gunfire crackled in the air, people outside of the casino ducked and screamed, according to video filmed by witnesses.

“We’re going to get trampled if we don’t go,” a bystander could be heard saying in a dramatic video of the incident. Confusion appeared to abound as those outside fled the scene with another person saying, “it’s fireworks.”

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Michelle Leonard, who was located in a booth near the main entrance of the arena, said the shooting just “kept going nonstop.”

Leonard said “mass confusion” unfolded as people tried to flee the scene. She said the shooting seemed like it went on for more than a minute.

“I had no idea of where it was coming from or where to run to,” Leonard said.

She said she injured her leg as she tried to escape.

Another witness, Jake Freeman, said he was standing on the rooftop of a nearby hotel when the shooting broke out.

“I had a bird’s-eye view” of the shooting, Freeman said in a phone interview with ABC News. He said he saw “crowds of people running” as people “dropped to the ground.”

“At the moment we didn’t realize that they were being shot,” he said.

Aldean, who performed at the country concert Sunday night, wrote on Instagram, “Tonight has been beyond horrific. I still dont know what to say but wanted to let everyone know that Me and my Crew are safe. My Thoughts and prayers go out to everyone involved tonight. It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night.”

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An official with McCarran International Airport said “an airport perimeter fence near the concert venue was breached by people fleeing the scene of the incident.”

“Airport staff responded and have transported those people to the designated evacuation site,” the officials said. “The fence line is once again secured.”

Flights in and out of the McCarran International Airport in Las Vegas were temporarily halted due to the incident.

ATF agents have responded to the scene and the FBI is assisting with the investigation. The FBI is also supporting local law enforcement efforts in Las Vegas.

Mandalay Bay Resort tweeted, “Our thoughts & prayers are with the victims of last night’s tragic events. We’re grateful for the immediate actions of our first responders.”

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The resort said in a statement that “law enforcement requested that we put hotels in the vicinity on lockdown to ensure guest safety.”

President Donald Trump tweeted, “My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!”

Nevada Gov. Brian Sandoval tweeted, “A tragic & heinous act of violence has shaken the #Nevada family. Our prayers are w/ the victims & all affected by this act of cowardice.”

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“Pray for Las Vegas,” Las Vegas Mayor Carolyn Goodman said via Twitter. “Thank you to all our first responders out there now.”