[UPDATED] Police Confirm 50 People Killed In Shooting Attack On Florida Club

Little more than 24 hours after the murder of singer Christina Grimmie in an Orlando venue on Friday night another shooting attack has occurred at a bar in the same city.

The BBC is reporting that a gunman opened fire inside Florida gay club Pulse at around 2am Sunday.

It is believed that several club goers have been injured and with over 40 shots reportedly fired inside the venue.

One witness who escaped the scene through the venue's back exit said people on the dancefloor hit the ground while those in the bar area escaped with him.

Police have now confirmed that the shooter is dead. They have also stated that "this is a mass casualty situation".

There have been no confirmed fatalities, earlier police were concerned that the shooter may have had a bomb and had taken hostages.

Club management were able to post a warning on Facebook as the attack began, writing: "Everyone get out of Pulse and keep running."

Another witness told CNN that "the shots did not sound like a regular handgun." Another witness has described the shooter's weapon as an assault rifle. 

Over a hundred people are estimated to have been inside the venue when the attack started.

It has now also been confirmed that controlled explosions were used by police at the site to distract the gunman so they could clear the club.

People who were in the area at the time of the shooting have posted on the club's Facebook page that they believe 20 injured victims have been taken to hospital from the shooting scene so far. Reddit users following the situation on scanners are reporting as many as 42 casualties.

Media talking to a mother of one of the victims said her son texted her from inside the club, telling her "he's rounded us up and is going to kill us."

[UPDATE :9.17pmAEST] Orlando police have briefed media with details of the attack. They have confirmed multiple fatalities amongst the victims of the shooting. There could be as many as twenty people killed.

Forty-two victims are being treated for gunshot wounds in hospital.

They have also confirmed the time that the incident began. The suspect became involved in a shootout with a police officer outside the club at 2am Sunday before barricading himself inside.

It is also now confirmed that once inside the club he took patrons hostage. It was three hours before police were able to enter the club and end the siege.

Police also say the shooter had a 'suspicious unknown device on his person' along with a handgun and an assault rifle. The bomb squad are working on disarming the device.

FBI are treating the attack as an act of terrorism and believe there are indications of links with radical Islam ideology. They describe the shooter as 'well prepared and not from the area'.

[UPDATE: 11.52pmAEST] Police have identified the attacker as 29 year-old Omar Mateen.

Mateen was killed at 5am by a SWAT team who entered the club to rescue the 30 hostages he held captive during the siege. The SWAT intervention is credited with saving at least 30 lives.

[UPDATE: 12.54amAEST] New York Times has stated that the number of fatalities is now numbered at 50 with another 53 club patrons wounded. They are reporting it as the "worst mass shooting slaughter in US history".