A moped rider is in critical condition after colliding head-on with a vehicle late Monday night in Nanakuli, police said.

The crash happened around 10:13 p.m. on Farrington Highway near Nanaikeola Street, according to the Honolulu Police Department’s Traffic Division, Vehicular Homicide Section.

Police said an unidentified man was traveling eastbound on a moped when he crossed into the westbound lanes and crashed into a vehicle driven by a 32-year-old man.

Emergency Medical Services transported the moped rider to an area hospital in serious condition, where he was later downgraded to critical. Police said he was not wearing a helmet at the time of the crash.

The driver of the vehicle remained at the scene and was not injured.

Speed, drugs and alcohol do not appear to be factors in the crash, police said. The investigation is ongoing.