A gunman turned a Las Vegas concert into a killing field Sunday night, murdering at least 50 people and injuring more than 200 others.

The suspect was identified as 64-year-old Stephen Paddock and authorities said they were "confident" Paddock's roomate, Marilou Danley, had been located. Officials previously described Danley as a person of interest.

Shooting in Las Vegas. People fleeing (video from the Mandalay Bay hotel) pic.twitter.com/hs98J5uK6T

— Eiki Hrafnsson (@EirikurH) October 2, 2017

Authorities said one on-duty officer was in critical condition and another was wounded in the shooting. Two off-duty police officers attending the concert were killed.

The gunman, who fired down on the concert from a room on the 32nd floor of the Mandalay Bay Hotel and Casino, was killed by police.

Clark County Sheriff Joseph Lombardo said authorities did not release the suspect's name but said he is a local resident. Lombardo said authorities believe this was a "lone wolf" attack but said they were looking for a roommate of the dead suspect as a person of interest.

Marilou Danley was described as an Asian female, about 4'11 and 111 pounds. Authorities told the public to keep an eye out for a Hyundai with a Nevada plate: 114B40 and a Chrysler with a Nevada plate 19D401.

Authorities first received calls about an active shooting at about 10:08 p.m.

Country music star Jason Aldean was performing at the Route 91 Harvest Festival when the gunfire erupted.

Aldean was performing his last song of the night. Initially, those in attendance said they thought the sound was firecrackers. But as the shots continued, Aldean stopped singing and some concertgoers could be heard yelling to each other to get down.

One witness told KSVN that he heard “hundreds of shots.” The gunfire was rapid and reportedly confused with firecrackers.

Marilou Danley is being sought for questioning re the investigation into the active shooter incident. If seen please call 9-1-1! pic.twitter.com/Z83XvcHejH

— LVMPD (@LVMPD) October 2, 2017

"It sounded like a machine gun," one vendor told Fox News. "It sounded like more than one machine gun."

Authorities said law enforcement swarmed the hotel and killed the gunman in a room on the 32nd floor.

Some concertgoers stayed behind to offer help to those around them.

“Everybody I saw breathing, I helped.” a concertgoer told Fox News.

Kodiak Yazzi, 36, said the music stopped temporarily and started up again before another round of pops sent the performers ducking for cover and fleeing the stage.

As the 40,000 fans in the crowd began to flee, Yazzi took cover and said he saw flashes of light coming from the Mandalay Bay hotel tower high above.

The area is now on lockdown. All clubs and businesses on the strip are closed.

University Medical Center spokeswoman Danita Cohen said the Las Vegas hospital is taking in people with gunshot wounds. She didn't have any more immediate information.

Zack, who said he was near the stage, told Fox News that his sister witnessed a concertgoer get shot in the head.

Country singer Jake Owen, tweeted, "Gun shots!!! Vegas. Pray to god. Love you guys. Love you Pearl."

The Associated Press contributed to this report

Story Update - 10/2/17 10:46AM via Fox News Partner

The suspect, who died of a self-inflicted gunshot wound, was identified as 64-year-old Stephen Paddock, a resident of Mesquite, Nevada. Police initially sought a womanbelieved to be Paddock's roommate, Marilou Danley, as a "person of interest." Detectives later made contact with her, and "do not believe she is involved with the shooting on The Strip."

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Clark County Sheriff Joseph Lombardo said an "excess of 10 rifles" were found in the room, but did not immediately reveal a motive. Paddock had been in the hotel room since September 28, according to Lombardo.

Authorities said two on-duty Las Vegas Metropolitan Police Department officers were injured during the shooting. One is in stable condition after surgery, and the other sustained minor injuries. Two off-duty police officers attending the concert were killed.

President Trump tweeted his condolences to the victims of the Las Vegas massacre, saying "My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!"

The gunman, who fired down on the Route 91 Harvest Festival from a room on the 32nd floor of the Mandalay Bay Resort and Casino, died from a self-inflicted gunshot wound just as police made entry to the room, according to LVMPD undersheriff Kevin McMahill.

Federal law enforcement sources told Fox News that Paddock "was known to local authorities" in Vegas, and multiple weapons were found in his hotel room.

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Blown out windows at the Mandalay Bay Hotel and Casino.  (Fox News)

At this time, federal officials do not see any connection to international terrorism and little is known about Paddock's motivation, sources said. The Islamic State terror group took credit for the Las Vegas shooting, saying the gunman converted to Islam months ago, but provided no evidence back up the claim.

The gunman's brother, Eric Paddock, told reporters outside his Central Florida home early Monday "an asteroid just fell on us," and said Stephen Paddock has no history of mental illness.

Paddock said his brother is "just a guy" and he "freaked," and had retired to Vegas because he liked gambling.

The Department of Homeland Security said Monday morning that the department is "closely monitoring" and helping partners investigate the tragedy, but at this time has "no information to indicate a specific credible threat involving other public venues in the country."

People scramble for shelter at the Route 91 Harvest country music festival after gun fire was heard on October 1, 2017 in Las Vegas, Nevada.  (Photo by David Becker/Getty Images)

People assist a wounded woman at the Tropicana during an active shooter situation on the Las Vegas Stirp in Las Vegas Sunday, Oct. 1, 2017.  (Chase Stevens/Las Vegas Review-Journal via AP)

Attorney General Jeff Sessions spoke with Sheriff Lombardo offering his full support, Department of Justice officials told Fox News.

Authorities first received calls about an active shooting at about 10:08 p.m. Country music star Jason Aldean was performing at the Route 91 Harvest Festival when the gunfire erupted.

Aldean was performing his last song of the night. Initially, those in attendance said they thought the sound was firecrackers. But as the shots continued, Aldean stopped singing and some concertgoers could be heard yelling to each other to get down.

One witness told KSVN that he heard “hundreds of shots.” The gunfire was rapid and reportedly confused with firecrackers.

"It sounded like a machine gun," one vendor told Fox News. "It sounded like more than one machine gun."

Authorities said law enforcement swarmed the hotel and killed the gunman in a room on the 32nd floor. Responding officers used an explosive device to force the door open into the room, law enforcement officials told Fox News.

Country singer Jake Owen, who performed before Aldean, told Fox News the gunfire was "non-stop."

"You couldn't tell where it was coming from. It was loud and non-stop," he said.

Some concertgoers stayed behind to offer help to those around them.

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“Everybody I saw breathing, I helped,” a concertgoer told Fox News.

Kodiak Yazzie, 36, said the music stopped temporarily and started up again before another round of pops sent the performers ducking for cover and fleeing the stage.

"It was the craziest stuff I've ever seen in my entire life," Yazzie told the Associated Press. "You could hear that the noise was coming from west of us, from Mandalay Bay. You could see a flash- flash- flash- flash."

As the 40,000 fans in the crowd began to flee, Yazzie took cover and said he saw flashes of light coming from the Mandalay Bay hotel tower high above.

Police officers stand at the scene of a shooting near the Mandalay Bay resort and casino on the Las Vegas Strip, Monday, Oct. 2, 2017, in Las Vegas.  (AP Photo/John Locher)

Another concertgoer told the Las Vegas Review-Journal the shots sounded like fireworks, and she hid in a sewer.

“It was a horror show,” Ivetta Saldana told the newspaper. “People were standing around, then they hit the floor.”

Retired FBI special agent and former national FBI spokesman John Iannarelli, who drove past the scene of the event just moments before the shooting took place, told Fox News the massacre was "obviously well-planned."

Iannarelli added the gunman used “expensive guns and ammunition.”

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Photos: Las Vegas Shooting

Iannarelli noted that FBI and police are going to speak with every friend and relative, and are conducting forensic review of the suspect's computers and phones.

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Jason Aldean stage hand describes concert shooting

The shooting at the sold-out Route 91 Harvest festival was the worst mass shooting in modern U.S. history. Forty-nine people were killed when a gunman opened fire at the Pulse nightclub in Orlando in June 2016.

Sunday's shooting came more than four months after a suicide bombing at an Ariana Grande concert in Manchester, England, that killed 22 people. Almost 90 people were killed by gunmen inspired by Islamic State terror group at the Bataclan concert hall in Paris during a performance by Eagles of Death Metal in November 2015.