PICTURED: Worst mass shooter in U.S. history - NYC-born Islamic extremist Omar Mateen, 29, who shot dead 50 and injured 53 in Orlando gay club massacre was homophobe who got angry when he saw two men kissing 

  •  
  • Suspected Islamic extremist opened fire inside Pulse gay club in Orlando in the early hours of this morning 
  • Law enforcement sources have identified the shooter as US citizen Omar Mateen, from Port St. Lucie in Florida
  • He killed at least 50 people and injured 53 and took party-goers hostage before being killed by police
  • Shooter, 29, was carrying a suspicious device, possibly a suicide vest, when he began shooting in the nightclub
  • Police used an explosive device to distract the gunman and rescue around 30 people who had been taken hostage
  • Police engaged in gunfire with the man and an officer was shot in the head, but he was saved by his helmet
  • FBI says gunman may have leanings to radical Islamic terrorism and it is being investigated as an act of terrorism
  • Took place four miles from where The Voice singer Christina Grimmie, 22, was shot dead at The Plaza Live on Friday

The suspected Islamic extremist who slaughtered at least 50 people after taking party-goers hostage inside a gay club in Orlando was angry after seeing two men kissing.

Law enforcement sources have identified the shooter, who was wielding an AR-15 assault rifle and a handgun, as US citizen Omar Mateen, 29, from Port St. Lucie in Florida.  

The gunman, who was born to Afghan parents, was carrying a suspicious device, possibly a suicide vest, when he opened fire on the dance floor inside Pulse in the early hours of this morning.

At least 50 people were killed and 53 others were injured in the shooting in the deadliest mass shooting in US history.

An FBI spokesman said the mass shooting is being investigated as an act of terrorism, adding that they are looking into whether this was an act of domestic or international terror, and if the shooter was a lone wolf. 

The FBI believe the gunman, who was shot dead by officers, may have leanings to radical Islamic terrorism. 

But his father, Mir Seddique, told NBC News his son became angry when he saw two men kissing in Miami several months ago.

This has nothing to do with religion, he said. We are saying we are apologizing for the whole incident. We werent aware of any action he is taking. We are in shock like the whole country.

Scroll down for video 

Pictured: US citizen Omar Mateen, 29, the suspected Islamic extremist who slaughtered at least 50 people inside a gay club in Orlando
Omar Mateen

Pictured: US citizen Omar Mateen, 29, the suspected Islamic extremist who slaughtered at least 50 people inside a gay club in Orlando

Attack: A woman sits on the ground outside the club while another party-goer, whose legs are covered in blood, stands beside her

Attack: A woman sits on the ground outside the club while another party-goer, whose legs are covered in blood, stands beside her

Response: Emergency services are pictured at the scene outside the Pulse nightclub in Orlando, Florida following this mornings shooting
Emergency services at the scene

Response: Emergency services are pictured at the scene outside the Pulse nightclub in Orlando, Florida following this mornings shooting

Distraught: A woman sits outside the nightclub following the mass shooting. Around 50 people were killed by the suspected gunman

Distraught: A woman sits outside the nightclub following the mass shooting. Around 50 people were killed by the suspected gunman

Friends and family members embrace outside the Orlando Police Headquarters during following the shooting at Pulse nightclub

Friends and family members embrace outside the Orlando Police Headquarters during following the shooting at Pulse nightclub

Ray Rivera, a DJ at Pulse Orlando nightclub, is consoled by a friend outside of the Orlando Police Department following the shooting

Ray Rivera, a DJ at Pulse Orlando nightclub, is consoled by a friend outside of the Orlando Police Department following the shooting

Demetrice Naulings (left) sobs outside the Orlando Police Headquarters where police are interviewing witnesses
People wait outside the emergency entrance of the Orlando Regional Medical Center hospital after the shooting at Pulse gay club

Demetrice Naulings (left) sobs outside the Orlando Police Headquarters where police are interviewing witnesses. Right: People wait outside the emergency entrance of the Orlando Regional Medical Center hospital after the shooting at Pulse gay club

Friends and family members embrace outside Orlando Police Headquarters following the deadly shooting in the early hours of this morning

Friends and family members embrace outside Orlando Police Headquarters following the deadly shooting in the early hours of this morning

SWAT: Orange County Sheriffs Department SWAT members arrive at the scene of the fatal shooting at Pulse Orlando nightclub in Orlando

SWAT: Orange County Sheriffs Department SWAT members arrive at the scene of the fatal shooting at Pulse Orlando nightclub in Orlando

Fatalities: At least 50 people were killed and 53 others were injured in the shooting. Pictured: An Orange County Sheriffs Department SWAT member

Fatalities: At least 50 people were killed and 53 others were injured in the shooting. Pictured: An Orange County Sheriffs Department SWAT member

Police, army and FBI surround the club after a suspected Islamic extremist wielding an assault rifle and a handgun killed about 50 people

Police, army and FBI surround the club after a suspected Islamic extremist wielding an assault rifle and a handgun killed about 50 people

An FBI spokesman said the mass shooting is being investigated as an act of terrorism
Pictured: Forensics at the scene of the shooting

An FBI spokesman said the mass shooting is being investigated as an act of terrorism. Pictured: Forensics at the scene of the shooting