UPD: (21:00)

Security forces revealed to US network NBC that Omar Mateen had called 911 and pledged allegiance to the Islamic State (IS), while he also made reference to the Boston marathon bombings. According to people in the club who had hidden in toilettes during the attack, the terrorist said he was faithful to ISIS while calling 911.

A suspected terrorist shooting at an LGBT nightclub in Orlando has left 50 people dead, police have confirmed, adding that the attacker had been killed following a hostage situation at the club.
Shots were fired at the Pulse Club, in the early hours of Sunday. Staff at the venue posted on Facebook: “Everyone get out of pulse and keep running” and there were quickly reports on social media of an ongoing attack.
Orlando police said the shooting was being treated as an “act of domestic terrorism” and had resulted in mass casualties, urging people to stay away from the area.
Several news outlets identified the gunman as Omar Mateen, a 29-year-old from Fort Pierce, Florida. The FBI said it had a “positive identification” of the shooter though it has not yet released a name as it is in the process of notifying his family.
The gunman was killed during a shootout with police, as they broke into the nightclub to rescue 30 people held hostage there. No motive for the attack has been offered by police. The Guardian has not been able to independently verify the identity of the shooter.

Police initially said about 20 people had been killed in the attack, with 42 injured, but later revised the death toll up to 50, with 53 hospitalised, including one police officer who had been shot in the head but whose “life had been saved by his Kevlar helmet”. They confirmed the gunman was armed with an assault rifle, handgun and “some kind of device”.
In a press conference on Sunday morning, an FBI spokesman said investigators believed the attacker may have had extremist beliefs, and would consider possible links to Isis, but cautioned they were pursuing multiple leads.

Source: Guardian