The city's mayor Buddy Dyer declared a state of emergency while police described the incident, the worst mass shooting in recent American history, as an act of terrorism.
Officials named Omar Mateen, a 29-year-old man from Fort Pierce Florida, as the gunman and said the killings were likely to be ideologically motivated.
At 2am on Sunday an officer engaged in a gun battle with Mateen after he opened fire in the club and started taking hostages.
In a bid to rescue hostages, police set off two “distractionary devices” at approximately 5am that blew apart a wall so a Swat team could enter the club. The suspect was killed in the gunfight.
Dyer said: "Today we're dealing with something that we never imagined and is unimaginable.
"Because of the scale of the crime I've asked the [Florida] governor to declare a state of emergency.
"We're also issuing a state of emergency for the city of Orlando so that we can bring additional resources to bear to deal with the aftermath."