More than 20 people were killed when a 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.
Sheriff Joseph Lombardo told reporters in a news conference that more than 100 people had been injured.
Police responded to reports of the shooting just after 10 p.m. (1 a.m. ET), and later killed the suspected gunman — a local resident — in the Mandalay Bay Resort, he added.
Officials were searching for a woman they identified as Marilou Danley, who they identified as an Asian female traveling with the unnamed suspect, 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.
The final night of the three-day Route 91 Harvest festival was taking place at Las Vegas Village when police said they were investigating reports of an "active shooter near/around Mandalay Bay Casino." The concert was being held across the street from the casino.
Country singer Jason Aldean was on stage performing when the first shots rang out. Aldean was named the Academy of Country Music's Entertainer of the Year.
- Popping of Gunfire in Las Vegas Caught on Camera 2:21
Meghan Kearney was at the festival when the shooting started.
“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.”