LAS VEGAS – There is no better way to explain the horrific scene in Las Vegas other than a war zone. That is the way officers described the carnage.

The suspected gunman behind the deadliest mass shooting in modern U.S. history was a 64-year-old Nevada resident who fired out of his room at the Mandalay Bay Resort and Casino before turning his gun on himself, police said.

Clark County Sheriff Joseph Lombardo said Stephen Paddock was confronted by SWAT officers on the 32nd floor of the facility, across the street from the Route 91 Harvest Festival concert, before killing himself, reported Fox News. There was an estimated 22,000 people attending the festival.

Clark County Sheriff

Clark County Sheriff Joseph Lombardo. (File photo.)

“He has no political affiliation, no religious affiliation, as far as we know,” Eric Paddock, his brother, told The Daily Mail.

“Our condolences go to the victims and all their families,” he added.

Massive Crime Scene Had the Appearance of a War Zone

Paddock is believed to have checked in as a hotel guest before the attack, which left at least 50 people dead and more than 200 injured, The Associated Press reported. However, that number has increased to more than 400, according to the Monday morning press conference. The updated figure was supplied by the Clark County Fire Department. Furthermore, the death toll is sure to rise with that many injured people.

“We’ve located numerous firearms within the room that he occupied,” Lombardo told the media.

He added: “We have no idea what his belief system was. Right now, we believe he was the sole aggressor and the scene is static.”

Responding officers used an explosive device to force the door open into the room to shoot Paddock, law enforcement officials told Fox News.

Motivation a Mystery for Now

Federal law enforcement sources told Fox News that Paddock “was known to local authorities,” in Las Vegas. But police in Mesquite, where Paddock lived, said he never had any run-ins with officers, the Desert Valley Times reported.

Police initially sought a woman believed to be Paddock’s roommate, Marilou Danley, as “person of interest.” Detectives later made contact with her, and “do not believe she is involved with the shooting on the strip.”

Eric told The Daily Mail that Danley is Paddock’s girlfriend.

The pair lived in a retirement community in Mesquite, about an hour northeast of Las Vegas.

Paddock apparently was the manager of the apartment complex, which was going to be searched early Monday morning, reported FOX 5 News.

Eric Paddock said there was “absolutely no indication he could do something like this.”

“He was just a guy,” Eric Paddock told The Daily Mail. “Something happened, he snapped or something, he was just a guy.”

Jason Aldean: ‘Beyond Horrific’

Country music star Jason Aldean had just taken the stage when the shooting began. He called the night “beyond horrific.” Moreover he said, “It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night.”

“Flip or Flop” star Tarek El Moussa left the country concert shortly before the shooting began. He shared his thoughts in an Instagram story early Monday morning.

“So I just left the Route 91 country concert in Las Vegas. I’m safe but there was an active shooting. Many people [were] shot and killed and [I’m] just really, really sad,” El Moussa shared. “So kind of bummed right now. Sucks that things like this happen. Have a good night.”

During the Monday morning press conference, Lombardo said they have uncovered nothing “derogatory” regarding Paddock. He had a prior traffic citation, and that was it.

The Las Vegas massacre Sunday night by Paddock has left at least 50 dead, making the tragedy the deadliest mass shooting in modern American history.

Deadly Massacres

Here are the deadliest shootings in U.S. history, according to Fox News.

  • Pulse nightclub massacre: Omar Saddiqui Mateen killed at least 49 people and wounded more than 50 inside Pulse, a gay nightclub, on June 12, 2016.
  • Sandy Hook Elementary School massacre: In 2014, Adam Lanza, 20, shot his mother dead in her home, then drove to the Connecticut school and fatally shot 20 children, between the ages of 6 and 7, plus six staffers at the school, for a total of 27 dead. He then killed himself.
  • Virginia Tech massacre: Virginia Tech student Seung-Hui Cho shoots dead 32 people in two locations of the school’s Blacksburg, Va., campus in April 2007.
  • Columbine High School massacre: In April 1999 two seniors at the Colorado school, Eric Harris and Dylan Klebold, fatally shot 12 students and one teacher and wounded 21 others before killing themselves.
  • Luby’s cafeteria shooting: George “Jo Jo” Hennard, an unemployed merchant seaman, shot and killed 23 people and wounded 20 others at Luby’s Cafeteria in Killeen, Texas, on Oct. 16, 1991. Hennard killed himself about 13 minutes after the rampage.
  • San Ysidro McDonald’s massacre: On July 18, 1984, James Huberty, 41, shot and killed 21 people and injured 19 others in and around a McDonald’s restaurant in San Ysidro, Calif. Huberty was later killed by a SWAT team sniper.
  • University of Texas tower shooting: On Aug. 1, 1966, University of Texas engineering student Charles Whitman climbed to the school’s iconic clock tower and opened fire. Whitman, a former Marine who had murdered his mother and wife earlier that morning, killed 13 and wounded 43 before he was gunned down by police.
  • Greenwood massacre: Racial violence in Tulsa, Okla., in 1921 left as many as 300 dead, nearly all African-Americans.
  • Ludlow massacre: Members of the Colorado National Guard plus guards hired by the Colorado Fuel & Iron Co. killed 19 striking coal miners in 1914. Many of the victims were minorities and immigrants.
  • Colfax massacre: On Easter Sunday of 1873, in the bloodiest racial attacks during Reconstruction, white Democrats slaughtered as many as 153 African-Americans at the Colfax, La., courthouse and later as other victims were being held prisoner.
  • Fort Pillow massacre: On April 12, 1864, Confederate soldiers shot dead or bayoneted to death 277 African-American soldiers fighting for the Union in Henning, Tenn. Nearly all of the victims had surrendered and dropped their weapons when they were killed.
  • Saltville massacre: Shortly after winning a battle in 1864 near Saltville, Va., Confederate troops killed between 45 and 50 wounded or captured African-American troops who had been fighting for the North.
  • Lawrence massacre: Pro-confederate guerrillas in 1863 killed as many as 200 civilians and burned down a quarter of Lawrence, Kan., a pro-Union community.
  • Spirit Lake massacre: In 1857 Native Americans of the Santee Sioux tribe killed 35 to 40 settlers and took four young women captive near West Okoboji, Iowa.
  • Bloody Island massacre: In 1850 federal troops killed as many as 200 Native Americans of the Pomo tribe on an island in Clear Lake, Calif. The attack was in revenge for the murder of two white settlers by members of another Native American tribe.

(Photo: Screenshot Fox News broadcast)