Editors note: this article has been updated to reflect the higher number of deaths as reported by numerous other outlets. 

A shooting inside an Orlando, Florida nightclub has left at least 50 people dead, it's been reported, with as many as 53 people transported transported for medical treatment.

The shooting happened early Sunday at Pulse Nightclub, a gay friendly club, and is being treated as an "act of domestic terrorism" by Orlando police.

Staff posted "Everyone get out of pulse and keep running" to Facebook, with one man commenting: "People on the dance floor and bar got down on the floor and some of us who were near the bar and back exit managed to go out through the outdoor area and just ran."

One man who was inside the club said the gunshots came "just one after another after another. It could have lasted a whole song."

"The shots did not sound like a regular handgun," Anthony Torres told CNN. "It sounded like it was shooting repetitively and it wouldn't stop," he said.

The gunman was killed by police following a shootout involving at least nine officers, one of whom was shot in the head, but whose “life had been saved by his Kevlar helmet,” according to police.

"It's appears he was organized and well-prepared," Orlando Police Chief John Mina said, adding that he was armed with an assault rifle, a handgun and "some type of (other) device on him."

An FBI spokesman said it was believed the attacker might have "leanings towards (Islamic terrorism), but right now we can't say definitely." 

Orlando Mayor Buddy Dyer confirmed the updated death toll from 20 to 50 and injured from 42 to 53. He further stated "Because of the scale of the crime I've asked the 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."

Officials are now confirming this tragic incident as "Worst mass shooting in recent US history" and FBI have updated their statement saying this is an indeeed an "Act of Terrorism". 

The suspect has been named as Omar Mateen, a 27-year-old US citizen from Port St. Lucie in Florida, which is nearly 150km from Orlando. 

Via The Guardian CNN and BBC image via