A state of emergency has been declared in Florida after a gunman opened fire inside a crowded gay nightclub in Orlando early Sunday (June 12), killing 50 people and injuring 53 in the worst mass shooting in US history. The Washington Post reported that relatives and law enforcement officials have identified the suspected shooter as Omar Mateen, a 29-year-old from Fort Pierce, Florida. According to the paper, Mateen's family is from Afghanistan and it is believed he was born in the United States. A handgun and assault rifle were found on the shooter after he died, said an Orange County sheriff. Florida Governor Rick Scott has declared a state of emergency. "We feel confident there are no immediate threats to the area or the United States of America," said FBI special agent Ronald Hopper, at an Orlando, Florida press conference following the shooting. Police have not identified a possible motive, but AFP, quoting a Federal Bureau of Investigation (FBI) official, said the bureau was investigating the shooting as an "act of terrorism". "Any time we have potentially dozens of victims in our communities, that I think we can qualify that as a terrorist activity. Whether that's a domestic terrorist or international one is something we'll get to the bottom of," said Danny Banks, of the Florida Department of Law Enforcement Office. Asked whether there was any reason to believe there was a connection to Islamic terrorism, FBI special agent Ron Harper said investigators would be looking into "all angles". "We do have suggestions that that individual may have leanings towards that particular ideology but we can't say definitively," he said. Reuters reported that FBI was still determining if it was a hate crime, a terrorist act or a violent crime. US President Barack Obama on Sunday ordered the federal government to provide any assistance necessary to local law enforcement officials investigating the shooting. Obama was briefed on the shooting by Lisa Monaco, Assistant to the President for Homeland Security and Counterterrorism, the White House said in a statement. Police said the shooter was dead, four hours after the incident began with a volley of gunfire in the Pulse nightclub in downtown Orlando, triggering a massive deployment of police and emergency vehicles. "We can confirm this is a mass casualty situation," the Orlando police said on their Twitter account. "The shooter inside the club is dead," they said in a separate tweet. Another tweet delivered after a briefing by the FBI the grim news that about 20 people had been killed inside the club. It was the second shooting incident in the city in just over 24 hours, coming shortly after singer Christina Grimmie was shot dead late Friday (June 10) by a gunman who stormed a theater where she had just finished a gig. Witnesses said the shooting erupted at around 2am local time (2pm Singapore time) amid throbbing music as the crowded club was nearing closing time. Speaking to Sky News, clubber Ricardo Negron, who was inside when the shooting began, described how the gunman raked the club with bullets. "People just dropped on the floor. I guess the shooter was shooting at the ceiling because you could see all the glass from the lamps falling," he told the network. He described hearing "non-stop firing" which probably lasted less than a minute but felt like a lot longer. "There was a brief pause in the shooting and some of us just got up and ran out the back. People have definitely been injured - or worse." Emergency vehicles swarmed the area, with at least one crisis command vehicle at the scene.