ATF: Firearms of Orlando gunman purchased legally

ORLANDO, Fla. (WOFL FOX 35) - The Federal Bureau of Investigation has taken the lead in the mass shooting at a nightclub in Orlando, Florida. Dozens were killed at Pulse Orlando nightclub early Sunday morning and several others were injured. 

A spokesman with the FBI says the agency first became aware of the gunman, Omar Mateen, 29, of  Port St. Lucie, Florida in 2013, when they said he made inflammatory comments to coworkers, alleging possible terror ties.

"The FBI thoroughly investigated the matter, including interview of witnesses, physical evidence and records checks.  In the course of the investigation, Mateen was interviewed twice. Ultimately, we were unable to verify the substance of his comments and the investigation was closed," said Ronald Hopper, an assistant agent in charge of the FBI's Tampa Division.

In 2014, Mateen again came to the attention of the FBI, because of possible ties to Moner Mohammad Abu-Salha, an American suicide bomber in Syria, Hopper said.  The FBI conducted an investigation, including an interview with Mateen but determined that the contact was minimal and did not constitute a substantive relationship or threat at that time.

"It has been reported that Mateen made calls to 911 this morning, in which he stated his allegiance to the leader of the Islamic State. We're looking into any and all connections, both domestic and international. We're going to be as transparent as possible, but we also want to be as accurate as possible," Hopper added. 

Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) said they have traced firearms belonging to Mateen.  Agents said he legally purchased a handgun and long gun in the last few days, which were believed to be used in the shooting incident.

As of late Sunday afternoon, federal agents had converged on Mateen's home and are now in the process of gathering evidence.