Authorities have detained a person of interest in the investigation of an arson fire at a Southern California mosque. Riverside County sheriff's officials said late Friday that the person was being questioned but declined to provide further details. No arrests were announced. Earlier the department released a statement calling the blaze "an intentional act" and saying it would use all available resources to investigate. Flames were reported just after noon Friday at the Islamic Center of Palm Springs. The fire was contained to the small building's front lobby, and no one was injured. Reymundo Nour, the mosque's acting imam, says people at the mosque described hearing a "loud boom" and seeing flames. Nour was not on the site at the time. Authorities provided no details on how the fire was set.