At least 50 concert-goers were killed on the famous Las Vegas Strip on Sunday night when shots were fired at Live Nation’s Route 91 Harvest outdoor country music event.

Police said that at least one gunman fired into the crowd at the outdoor The Lot venue from an upper level room at the Mandalay Bay hotel and casino, leaving more than two hundred people injured. A suspect, who has been confirmed as a local resident, was shot dead by police on the 32nd floor of the hotel, Sheriff Joe Lombardo said at a briefing.

The attack came during the last performances on the final night of the three-day Route 91 country music festival, which has been held for the past four years on a lot on Las Vegas Boulevard across from the hotel.

The Mandalay Bay is on lockdown, according to reception. Guests have been told to stay in their rooms, and the hotel is not letting people into the building.

Though authorities believe the suspect was a “lone wolf”, Lombardo said police are also searching for Mari Lou Danley, identified as an Asian woman who was with the suspect at the time of the attack.

A woman at the concert who did not provide her name told CNN she saw several people shot, including one man who she tried to help by driving him to safety.

“We hit the floor, so everyone was just literally laying on top of each other, trying to get out of the way,” she said.

“The shots just kept coming so we were going down, and when we got down there was a man who was shot right there. They were trying to take him out, he was all bloody, and he was unconscious. One of my friends was helping him out and they got him out and we ran.”

Live Nation has yet to comment publicly on the tragedy.

Route 91 was founded in 2014 as a co-production between Live Nation and MGM Resorts International. Brian O’Connell, Live Nation president of country touring, said at the time: “Las Vegas and country music are synonymous with over the top events, and we know that Route 91 Harvest will deliver the latest, greatest experience for fans from all over the world.”