An 84-year-old man died and a 79-year-old woman was seriously injured in a single-vehicle crash in East Oahu Monday, Honolulu police said.

The crash occurred on Kalanianaole Highway at about 7:35 p.m.

Police said a white 2014 Toyota Corolla occupied by a man and woman of Hawaii Kai was traveling eastbound on the highway when the vehicle lost control and struck a guardrail in an area east of Hanauma Bay Road.

The 84-year-old passenger was pronounced dead at the scene, police said. He was not wearing a seat belt at the time of the crash.

The 79-year-old driver was taken in serious condition to The Queen’s Medical Center.

Police said speed may be a factor in the crash. Drugs and alcohol were not factors.

Police are continuing their investigation.

This is the 55th traffic-related fatality on Oahu this year compared to 46 at the same time last year.