A police car was hit in a four-vehicle chain-reaction collision in Waipahu.

The crash happened about 1 p.m. when one vehicle rear-ended another vehicle that was stopped in traffic near Lumiaina and Lumiauau streets. The second vehicle rear-ended the third vehicle, which hit the unmarked police car that was also stopped in traffic, police said.

The driver of the second vehicle complained about pain to the back but refused treatment at the scene. No one else was hurt, and no one was arrested.