A gunman who federal authorities say had possible ties to Islamist terrorism opened fire early Sunday morning at a packed Florida nightclub, killing approximately 20 people and wounding scores more in a bloody scene that ended hours later when police stormed the building and killed the suspect.

The shooting in Orlando at Pulse, which bills itself as "the hottest gay bar" in the city and was packed with more than 300 people, was reported minutes after 2 a.m. Sunday. In addition to those killed inside the club, at least 42 people were taken to area hospitals. Dozens of party-goers remained hostages in the club for several hours after the initial shooting, prompting SWAT teams to pour inside. Shortly after 6 a.m. local time, Orlando police tweeted that the gunman had been killed.

The gunman, whose identity was not immediately released, “may have leanings” toward radical Islam, FBI Special Agent in Charge Ron Harper said when asked by Fox News whether the suspect had ties to Jihadist terror groups. Harper said the investigation is looking into possible threats made previously by the suspect in connection to radical Islam groups. He said the agency is still investigating and has yet to confirm any role a terror group may have played in the mass shooting.

“There are allegations the individual made threats in the past to having ties to terrorist organizations,” Harper told Fox News.