A 27-year-old woman was struck by a police car early Sunday morning while riding her bicycle in Kailua.

The police car struck the bicycle at about 12:30 a.m. near the intersection of Hamakua Drive and Kailua Road. Paramedics took the woman to the hospital in critical condition, according to an Emergency Medical Services report. Her condition was upgraded to serious at the hospital, police said.

The officer was not injured.

The Traffic Division opened a negligent injury and administrative investigation. No arrests were made.

Police closed the Kailua-bound lanes of Kailua Road between Kainehe Street and Hamakua Drive until about 5 a.m. while they investigated the crash.

The crash marks the second accident in three days involving a police car and serious injuries.

Early Friday morning, a police officer was seriously injured when a Mercedes sedan leaving a driveway and a marked police vehicle collided on Kapiolani Boulevard near Kona Iki Street at 12:20 a.m. Friday.

Paramedics took the 37-year-old woman officer and the 66-year-old man driving the Mercedes to the hospital in serious condition.