The cause of a fire at a two-story apartment building in Waikiki on Sunday that resulted in two fatalities was accidental, according to the Honolulu Fire Department.

The origin of the fire at 1829 Kaioo Drive was in the bedroom of a first-floor unit, according to the HFD investigator. It was caused by arcing from an extension cord.

On Sunday, HFD received a 911 call at 3:02 p.m. for the three-alarm fire in Waikiki. Thirteen units staffed with about 51 personnel responded and found the building engulfed in smoke and flames.

Firefighters brought the fire under control at 3:26 p.m. and extinguished it at 3:42 p.m.

Two occupants were found deceased in their second-story home, HFD said. Two occupants from the first-floor unit were injured.

Smoke detectors were present, but occupants and witnesses said they did not hear any audible activation.

Damages are estimated at about $1.2 million to the property, and $84,000 to its contents.