Muslims mosque set on fire on Eid al-Adha by arsonists in Florida

A fire that broke out early Monday at the Fort Pierce, Fla., mosque where Orlando massacre shooter Omar Mateen worshiped is considered arson, according to investigators.

"Evidence has revealed that this fire was set intentionally," St. Lucie County Sheriff's Maj. David Thompson told reporters.

A 911 call about 12:30 a.m. alerted authorities that flames were coming out of Islamic Center of Fort Pierce, authorities said.

There were no injuries reported, and the extent of the damage has not yet been determined.

According to Thompson, investigators were able to find surveillance video that shows someone approaching the east side of the mosque.

"Immediately after the individual approached, a flash occurred and the individual fled the area," he said.

He said the sheriff's office is asking the FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives to join the investigation being conducted by local authorities and the state fire marshal's office.

Additionally, he said, technicians are working to enhance the surveillance video so it can be released to the public in order to turn up leads in the case.

Mateen, who lived in Fort Pierce, killed 49 people at Orlando's Pulse nightclub in June and was known to worship at the mosque. Mateen was killed in a shootout with police.

Leaders at the Islamic Center have said that since the nightclub shooting the facility has received threats and that security had been stepped up.

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Thompson was asked about any coincidence between the blaze and the 15th anniversary of the 9/11 attacks.

"We all know the implications of the date and the time of year that this is, the 9/11 anniversary. Is that related? I would not want to speculate but certainly that is in the back of our minds," he said.

Monday is the beginning of Eid al-Adha, the four-day Islamic festival of sacrifice. Because of the extra traffic that was anticipated, Thompson said sheriff's deputies were scheduled to be on hand to assist with parking and traffic flow around the mosque.

"This is a terrible tragedy, not only for the Islamic Center, but for our community,” he said.