A mosque attended by the Orlando shooter has been hit by an apparent arson attack

A mosque previously attended by Omar Mateen, the perpetrator of the Pulse nightclub massacre in Orlando, has been set on fire in what investigators called a case of arson.

The fire at the Fort Pierce Islamic Center coincided with the first day of the Muslim holiday of Eid al-Adha.

The St. Lucie County Sheriff’s Office said they believed the fire is the work of an arsonist based on surveillance video showing an individual arrived at the building on a motorcycle around 12:30 a.m. holding some sort of fluid. Video from the surveillance camera published by local TV station CBS 12 shows a bright flash from the side of the building and then a man running away.

The fire was reported to authorities shortly after, and the fire department responded to put the blaze out. No one was injured in the fire, but authorities told CBS 12 there was substantial damage to the building, both inside and out.

Major David Thompson of the sheriff’s office told reporters that there had been no recent threats against the Center, and that they had requested the FB, the Bureau of Alcohol, Tobacco and Firearms and the state fire marshal’s office join the investigation.

“This is a horrible tragedy,” Thompson told ABC News, “not only for the Islamic Center, but also for our community.”

In a statement announcing the attack on its Facebook page, the Islamic Center offered an alternate location for worshippers to attend services for Eid al-Adha and asked people to keep the mosque in their prayers.

Mateen, who died in a June attack on the Orlando Pulse nightclub that killed 49 people, used to attend services at the Center. In a June interview with the Palm Beach Post, the Center’s Imam Syed Shafeeq Rahman said he never once had a conversation with Mateen, who would come in for prayers then leave shortly after. News of the attack shocked both him and his congregation.

“I just cried when we prayed, in front of everyone,” Rahman told the Post. “I cried for all the people who died. Of course, it is a big shock for us.”

This isn’t the first time the mosque has had to deal with hatred since Mateen’s death. A Muslim man was beaten outside the center in early July, with the attacker reportedly using racial slurs during the attack. A group of 66 motorcyclists held a “patriot cruise” around the mosque in late June, revving their engines when they passed the door.