The shooter has been identified by authorities as Omar Mateen, who allegedly pledged allegiance to ISIS in a phone call to emergency services.
The chaos began at approximately 2:00am local time when gunfire could be heard inside the club at around closing time. Mateen, armed with an assault rifle and a handgun soon engaged in a gun battle with police officers and venue security. Police also made a statement, reporting that the shooter was wearing a 'suspicious device', believed to be a bomb.
In the following hours, Mateen took dozens of hostages and a stand-off with local authorities ensued.
At 5:00am, Orlando Police stormed the building, detonating explosives and breaking through a wall with an armoured car. The operation was able to rescue 30 hostages, however it is unclear as to whether more patrons were killed in the relief attempt.
In a statement issued by the Orlando Police Department, "[our officers] were all shaken by what they saw inside that club".
The club itself, which is a gay nightclub, made a post to its Facebook page urging patrons to flee the scene.
Mateen was a U.S. citizen of Afghan descent, and was apparently investigated by the FBI at some point in time for having ties with Islamic extremism.
Whilst the immediate crisis has come to an end, details are still unclear and are subject to change.
Hugh McFarlane