Speeding, wet roads and bald tires are to blame for a serious crash that shut down a part of the Inland Island Highway, according to RCMP crash investigators.

The crash happened south of Courtenay around 6 p.m. Saturday when an older-model BMW was trying to overtake a Honda SUV and lost control, causing it to spin out and slam into an unmarked police cruiser.

RCMP crash analyst Sgt. Brian Nightingale said the officer had just finished conducting a traffic stop and the cruiser was parked at an emergency U-turn lane.

"[The officer] received a reading on his radar that a vehicle was coming up behind him that was travelling quite fast.

"[The driver's] loss of control was while he was overtaking another car. He then rotated completely 180 degrees and went into the centre median backwards, where he struck the police car," Sgt. Nightingale explained.

The two occupants of the BMW suffered serious injuries and were taken to hospital.

The police officer had minor injuries and did not require hospitalization.

With files from CTV Vancouver Island's Gord Kurbis