Authorities in Florida are investigating a fire at a mosque that was attended by the gunman in the deadly Orlando nightclub shooting.

Maj. David Thompson of the St. Lucie County Sheriff's Office told a news conference officials received a report around 12:30 a.m. Monday about a fire at the Islamic Center of Fort Pierce. Firefighters extinguished the fire.

The mosque was attended by Omar Mateen, who opened fire at the Pulse nightclub on June 12 in a rampage that left 49 victims dead and 53 wounded. It was the worst mass shooting in modern U.S. history.

Thompson says it's too early to tell if the fire was an accident or was intentionally set. He also declined to speculate on whether the Sunday anniversary of the Sept. 11, 2001, terrorist attacks played a role in the fire.