Investigators Share Video of Possible Arson Suspect From Omar Mateen's Mosque Fire Investigators are investigating arson as the cause of the blaze.

 -- Investigators released video showing a possible suspect in a fire that authorities believe was deliberately set at the mosque that had been attended by Omar Mateen, the shooter in the Orlando nightclub massacre.

The St. Lucie County Sheriff's Office said surveillance footage shows what appears to be a white or Hispanic male arriving at Florida's Islamic Center of Fort Pierce on a Harley-Davidson-style motorcycle at approximately 11:38 p.m. on Sunday.

In the video, a man is seen approaching the building from the northeast side, and then a flash can be seen, according to the sheriff's department. The male is then seen running from the building. He appears to be carrying "paper and a bottle of some type of liquid," the sheriff's department said in a statement.

The department added that he can be seen waving his arm around immediately after the flash, possibly indicating that he burned his hand.

Authorities are asking anyone who recognizes the individual from the video to come forward.

Wilfredo Amr Ruiz, a spokesman for the Council on American–Islamic Relations in Florida, said in a press conference this afternoon that less than an hour before the mosque was set on fire there were people inside. Ruiz added that Omar Mateen did not regularly attend this mosque, although Mateen's family did.

Ahmed Bedier, a Muslim man and the president of United Voices for America, added that "an attack on any house of worship is an attack on all houses of worship," and urged the community to "stick together."

The federal Bureau of Alcohol, Tobacco, Firearms and Explosives announced in a statement today that special agents from its field office in Fort Pierce and certified fire investigators from its Miami field division are assisting the FBI and that the arson is being treated as a hate crime.

The St. Lucie County Sheriff's Office is also investigating the arson, along with the St. Lucie County Fire District and the Florida State Fire Marshal's Office, the sheriff's office announced this morning.

Emergency responders received a call at about 12:31 a.m. Monday reporting a fire at the Islamic Center of Fort Pierce, the county sheriff's office said. County fire crews responded and extinguished the fire.

Investigators said evidence points to an intentional fire.

Surveillance video shows an individual walking up to the east side of the building before a flash and the start of a fire, Major David Thompson of the sheriff's office, said at a press conference this morning.

The blaze broke out just hours after the passing of the 15th anniversary of the 9/11 attacks, three months after the Jun. 12 massacre at the Pulse nightclub in Orlando and on the same day as the Muslim holiday of Eid al-Adha.

“Right now, I don’t want to speculate on a motive," Thompson said. "We all know the implications of the date and the time of year. This is the 9/11 anniversary. Is that related? I would not want to speculate, but it is in the back of our minds.”

“This is a horrible tragedy," he added, "not only for the Islamic Center but also for our community.”