Tucson Fire is investigating the cause of a late-night duplex fire on Tucson's south side, authorities said.
At about 12:15 a.m., firefighters responded to multiple 911 calls of heavy smoke and flames coming from a duplex in the 3700 block of South Clark Avenue.
Fire crews pulled a hose line through the front door, checking for occupants and extinguishing the flames.
Additional crews checked the adjoining unit, ensuring that the fire hadn't spread to it. Although a large amount of smoke was present, Tucson Fire confirmed that the fire was contained to a single unit of the duplex.
No one was inside the unit and the fire was called under control 12 minutes after the first crew arrived, according to a news release.
Efforts are being made to find the tenants and determine the cause of the fire, which remains unknown at this time.
