Oakland Fire Chief Teresa Deloche-Reed says at least another 13 people are unaccounted for as of Saturday morning.
Deloche-Reed says the fire department still must do a thorough search of the building.
The fire started about 11:30 p.m. Friday. It tore through the building during an event featuring musician Golden Donna's 100% Silk West Coast tour, the East Bay Times reports.
Authorities told KTVU-TV about 50 people were in the building, which houses a group of artists and their studios.