A 59-year-old motorcyclist was critically injured Wednesday morning in a collision with a sedan on Ala Wai Boulevard near McCully Street in Waikiki, according to Honolulu police.

The crash occurred at about 9:41 a.m. when the westbound motorcyclist was struck by a sedan driven by a 53-year-old man who was also traveling westbound and changing lanes.

Emergency responders transported the motorcyclist to a nearby hospital in critical condition. He was not wearing a helmet at the time of the crash, police said.

The driver of the sedan was uninjured and remained at the scene.

Police said speed, alcohol, and drugs do not appear to have been factors in the collision, which remains under investigation.