The fire, reported at 12:22 a.m. in a sixth-floor apartment on Cambon Drive, was caused by a smoker who was too close to an oxygen tank, Lt. Mindy Talmadge said.
The flames spread through the apartment, but firefighters were able to extinguish the blaze by 12:50 a.m.
The two occupants of the unit were taken to a hospital, according to Talmadge. She said both victims were conscious and alert, but she did not immediately have an update on their condition.
The fire caused an estimated $40,000 in damage to the building and $100,000 in damage to its contents, Talmadge said.
The building has been deemed safe and all other occupants have been allowed to return home, she said.
Parkmerced officials were not immediately available to comment on the blaze.