City's  Mayor Buddy Dyer told media: "50 people died in Pulse nightclub shooting."

A gunman, who was wielding an assault-type rifle and a handgun, took hostages and opened fire inside the Pulse nightclub which left 53 others injured.

The attacker was identified by officials as Omar Mateen.

Orlando Police Chief John Mina called the attack as one of the worst mass shootings in the history of the US.

"It is one of the worst mass shootings in our nation's history," he told media.

Video footage being shared earlier on social media show several emergency vehicles rushed at the spot.

The police said the shooting started at 2 am.

 

Police vehicles, including a SWAT team, reached the spot after the incident started.

Orlando Police tweeted: "OPD first responders and SWAT rescued at least 30 people from inside the club and brought them out alive."

The night club earlier posted on their Facebook page: "Everyone get out of pulse and keep running."

Orlando authorities were quoted as saying by CNN that they consider the violence an act of domestic terror.

One Facebook user Ricardo J. Negron Almodovar, who claimed he was inside the bar, wrote on his Facebook page: "I was there. Shooter opened fire @ around 2:00am. People on the dance floor and bar got down on the floor and some of us who were near the bar and back exit managed to go out through the outdoor area and just ran. I am safely home and hoping everyone gets home safely as well ."