Firefighters from five departments battled a fire at the abandoned Safety Department building at the defunct Kings Park Psychiatric Center early Wednesday, extinguishing the blaze in about 90 minutes, Suffolk County fire officials said.
The building once housed the old fire and police departments for the state facility, but has long been abandoned, its windows and doors boarded up.
Officials said state arson and fire marshals are investigating the cause of the blaze, but said it was likely caused by vandals or vagrants.
The fire was reported at about 2 a.m.
Officials said firefighters from Kings Park, Commack, Northport, East Northport and Nissequogue all responded.
There were no reported injuries.
Photos from the scene show black smoke and flames pouring out of upper-floor windows in the brick two-story structure. Additional information was not available on Wednesday.