A police officer in his 30s was taken to The Queen's Medical Center in stable condition early this morning after the car he was sitting in was rear-ended by another vehicle on the Moanalua Freeway.

Police said the incident happened about 3:45 a.m. in the west-bound lanes of the freeway near the Kahuapa'ani Street overpass.

The officer, who was on duty, was sitting in his car on the shoulder of the freeway after writing a ticket when his car was struck from behind, police said.

A man in his mid-20s who was a passenger in the other car was taken to Queen's in serious condition with head and neck injuries.

The driver of the other car was arrested at the scene and taken to the main police station for questioning.