At least 50 people were killed and more than 400 injured after a gunman opened fire at people attending a country music festival on the Las Vegas strip on Sunday night. Several police officers were among the dead.

The Islamic State group claimed responsibility for the attack through its news agency, Reuters reported. The Federal Bureau of Investigation, however, has refuted the extremist group’s claims. The investigating agency said there was no evidence linking the accused with any any international terrorist organisation.

The shooter, identified as 64-year-old local resident Stephen Paddock, opened fire from the 32nd floor of the Mandalay Bay Hotel. Las Vegas Sheriff Joseph Lombardo said the police had found at least 10 rifles in his room at the hotel, CNN reported.

“The primary aggressor is dead...the scene is static,” Lombardo said, adding that Paddock had killed himself the hotel room. The woman believed to be the shooter’s companion, Marilou Danley, is no longer being pursued as a “person of interest”, the police said, according to CNN.

Thousands of people attend the country music festival – the Route 91 Harvest Festival – that was targeted. Several videos on social media showed hundreds of people fleeing the site of the shooting.

The Las Vegas Hospital is treating several people for gunshot wounds, Al Jazeera quoted University Medical Center spokesperson Danita Cohen as saying.

The police have not yet ascertained whether Paddock had any links with any militant groups. The Las Vegas sheriff said they had to find what his motive was before establishing that the shooting an act of terrorism.

Part of the Las Vegas Strip and Interstate 15 was shut down. The McCarran International Airport, which is close to the Mandalay Bay Hotel, had temporarily halted flights in and out of the Las Vegas Airport after the mass shooting.

Country singer Jason Aldean, who was performing at the concert at the time of the attack, said he was shocked by the incident. “Tonight has been beyond horrific,” Aldean wrote on his Instagram page. “I still don’t know what to say but wanted to let everyone know that me and my crew are safe...It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night.”