A gunman reportedly linked to ISIS has opened fire at a gay nightclub in Orlando, Florida, US, killing nearly 50 people and injuring at least 53.
The massacre at Pulse club follows an ISIS call for terror attacks in the US during the holy month of Ramadan, CNN reported.
The Afghani-origin gunman, Omar Mateen, was born in New York and had worked as a security officer at G4S Secure Solutions since 2007.
Mateen, who had a licence to possess firearms, carried an assault rifle and a handgun into the club on Sunday.
Though ISIS news agency Amaq claimed that an ISIS fighter carried out the mass firing, no evidence of link between Mateen and jihadist militant group was found.
Police broke into the club with an armoured vehicle and killed the shooter in an exchange of fire.
Commenting on the tragic shooting in Orlando, US President Barack Obama said: "Although it's still early in the investigation, we know enough to say that this was an act of terror and an act of hate.
"This massacre is therefore a further reminder of how easy it is for someone to get their hands on a weapon that lets them shoot people in a school, or in a house of worship, or a movie theatre, or in a nightclub.
"And we have to decide if that's the kind of country we want to be. And to actively do nothing is a decision as well."
The FBI is investigating the attack in partnership with local law enforcement.