Fire investigators are trying to determine the cause of a fire that heavily damaged a duplex early Wednesday on Lavinia Street, according to a news release from the Baton Rouge Fire Department.

Firefighters arrived at 631 Lavinia St. just before 1 a.m. to find fire coming from one of the units in the duplex. Firefighters were able to contain the fire mainly to that duplex, but nearby buildings sustained minimal fire and smoke damage.

The duplex that caught fire was supposed to be vacant, but a homeless person was found to have been living there. No injuries were reported.

Damage to the duplex is estimated at $55,000.