Police arrested David Prado, 45, of Alameda, for arson in connection with the fire, which was reported at 2:47 a.m. at a four-unit, two-story building in the 3200 block of Briggs Avenue near Lincoln Park, Alameda fire Capt. James Colburn said.
Prado's arrest came after firefighters rescued him from the balcony of his apartment, the fire captain said. Other residents are believed to have jumped from their balconies to safety.
None of the residents reported any injuries.
Firefighters fought the blaze defensively and were able to bring it under control at 5:06 a.m., Colburn said.
One firefighter was taken to a hospital with heat exhaustion and has been released, and three were treated for minor injuries at the scene, Colburn said.
The American Red Cross is assisting the displaced residents.
Police and fire investigators are continuing to investigate the fire's exact cause and point of origin.