At least fifty people were killed and 53 other injured in the mass shooting which occurred at a gay nightclub in Orlando, Florida on Sunday.

The shooter, who has been identified as 29-year-old Omar Mateen, was killed in a shootout with police after he had stormed the building with a rifle and handgun and held hostages for three hours.

It is believed that there were 300 people in the club when eleven police officers and three sheriff’s deputies stormed the building.

According to NBC, Mateen called the 911 emergency telephone number before the attack and swore allegiance to Islamic State (IS).

IS claimed responsibility for the shooting in a statement on its affiliated Amaq news agency, but it is not clear whether the attack was planned beforehand.

US President Barack Obama called the attack, which constitutes the deadliest shooting in the recent history of the USA, an “act of terror and hate”.

A minute of silence was observed across the USA on Sunday and flags at federal buildings will be flown at half mast until sunset on Thursday. State of emergency has been declared in city of Orlando and the surrounding Orange County.

Mateen was an US citizen of Afghan descent, who had been born in New York and lived in Florida. He had not been placed on a terrorism watch list and he had legally purchased guns in the past few days.