Reported by NBC News:

More than 50 people were killed in the worst mass shooting in modern American history when a “lone wolf” gunman opened fire into an outdoor country music festival from the 32nd floor of Las Vegas’ Mandalay Bay Resort and Casino on Sunday night, police said.

More than 200 people were injured in the mass shooting as performer Jason Aldean was on the stage, Sheriff Joseph Lombardo said at a news conference.

The gunman was identified by law enforcement officials as 64-year-old Stephen Paddock, a resident of Mesquite, Nevada.

Watch Live: NBC News Special Report on Las Vegas Shooting

Police responded to reports of the shooting just after 10 p.m. (1 a.m. ET), and the suspect was fatally shot in the Mandalay Bay Resort, officials said.

Authorities found several weapons in Paddock’s hotel room, law enforcement officials reported. It was not immediately clear what kinds of weapons were located.

Meghan Kearney described the chaotic scene as shots started ringing out.

“We heard what sounded like firecrackers going off. Then all of a sudden we heard what sounded like a machine gun. People started screaming that they were hit… When we started running out there were probably a couple hundred [people] on the ground,” she told MSNBC.

“People kept dropping and dropping… People were getting shot one foot away from us,” she said. “People were trying to save their friends. There were gunshots everywhere. Helping them would’ve meant that we got shot too.”

“We believe there’s a couple off-duty officers that were attending the concert that may have died,” Lombardo said.

Image: Marilou Danley
Marilou Danley is wanted by police for questioning in connection with the shooting in Las Vegas on Oct. 1. LVMPD

Officials were searching for the suspect’s companion, Marilou Danley, a 62-year-old Asian female, said Lombardo.

Police also asked for the public’s assistance in finding two vehicles: a Hyundai Tuscon with the Nevada license plant number 114B40; and a Chrysler Pacifica Touring with the Nevada number 79D401.

Earlier, police shut down the area and urged the public to stay away. Flights in and out of the airport were temporarily halted.

Aldean, who was named the Academy of Country Music’s Entertainer of the Year in April 2017, was on stage performing on the final night of the three-day Route 91 Harvest festival at the Las Vegas Village when the first shots rang out.

Shortly after, police said they were investigating reports of an “active shooter near/around Mandalay Bay Casino.” The hotel is across the street from the festival grounds.

Aldean later said via Instagram that he and his band were safe.

Popping of Gunfire in Las Vegas Caught on Camera 2:21

Jon Bessette said he was attending the festival when he heard gunshots.

“The band ran off stage and it was pandemonium,” said Bessette. “Everyone was running, people were getting trampled.”

Several artists performing at the music festival also reported hearing gunshots.

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

This is a developing story. Please check back for updates.

Richie Duchon and Andrew Blankstein reported from Los Angeles. F. Brinley Bruton, Rachel Elbaum and Yuliya Talmazan reported from London. Pete Williams reported from Washington.