Firefighters and police were called to a blaze at the Islamic Center in Joplin, Missouri – where around 125 members of the local Muslim community pray.
“The building was completely destroyed,” said Sharon Rhine, a spokesman for the local Jasper County Sheriff’s office.
No one was wounded in the incident.
“No one was apprehended. They don’t want to call it a hate crime without information or knowledge of having someone to charge,” Rhine said.
Monday’s fire followed an attack on July 4, when an unidentified suspect threw a petrol bomb onto the roof of the same mosque, causing minor damage.
FBI spokesman Bridget Patton said both incidents occurred in the middle of the night, but said the FBI would “wait to determine the cause of the fire”.
“If it is determined that the attack was intentional, we will conduct and investigation to see if there is any correlation between this fire and that of July 4,” Patton added.