Who is Omar Mateen, the Orlando nightclub shooting gunman?

The gunman who committed a mass shooting at Pulse nightclub in Orlando, Florida has been identified by the FBI as Omar Saddiqui Mateen.

NBC is reporting that Mateen called 911 and declared allegiance to ISIS before the attacks, but this has not been confirmed by law enforcement.

Mateen is reportedly a U.S. citizen from Fort Pierce, Florida and is not believed to have had a criminal record. WFTV is reporting that law enforcement was aware of Mateen before the nightclub shooting, but was not the target of any active investigation.

CNN is reporting that Mateen, 29, worked as a private security guard. His employer confirmed that information Sunday afternoon.

John Kenning, the regional CEO for G4S, the security company where Mateen was employed, released a statement on the shooting:

Mr Kenning said: "We are shocked and saddened by the tragic event that occurred at the Orlando nightclub. We can confirm that Omar Mateen had been employed with G4S since September 10, 2007. Omar Mateen was not on duty at the time of the incident. We are cooperating fully with all law enforcement authorities, including the FBI, as they conduct their investigation. Our thoughts and prayers are with all of the friends, families and people affected by this unspeakable tragedy." Further updates to the above will be provided as appropriate.

Mateen's parents are from Afghanistan, according to CBS.

Approximately 50 people were killed and over 50 injured in the attack on the gay nightclub that happened early Sunday morning. The gunman, officially identified as Mateen, is also dead. The attack is the worst mass shooting in U.S. history.

This is a developing news story, visit WFTV for updates.