Coachella, Calif. - A fire at a California mosque on Friday was being investigated as possible arson, officials said.The Riverside County Sheriff's Department said on Twitter that the blaze, which spewed smoke and flames in the lobby but was quickly contained and caused no injuries, was under investigation to find out whether it had been set deliberately.Coming barely a week after a Muslim couple with roots in Riverside County opened fire in nearby San Bernardino County, the blaze raised concerns of an anti-Islamic backlash.The Riverside County Fire Department said the fire was reported at 12:09 p.m. and contained to the lobby 35 minutes later. There was smoke damage but no injuries, the agency said.A spokeswoman for the California Department of Forestry and Fire Protection, which operates the Riverside department under contract with the city, said she had no indication that the fire had been set deliberately.A spokeswoman for the FBI in Los Angeles, Laura Eimiller, said the agency was helping the Riverside County Sheriff's Department investigate."We're responding to the mosque to assist local law enforcement partners," Eimiller said. "Anytime there is a concern that a house of worship may have been targeted, we would respond and have an investigative interest in the cause and whether or not it was deliberate."Local television station KESQ reported that officials at the Islamic Society of Palm Springs had said the building had been firebombed, but it did not name the officials. Officials at the mosque did not answer repeated phone calls placed by Reuters.CalFire spokeswoman Jennifer Fuhrman said that the agency was investigating the cause of the blaze, with an update possibly coming later on Friday.