It hit the police car which was stopping the traffic.

它（那辆车）撞在了正在拦截车流的警车上。

youdao

The police car signalled to us to pull in.

警车发出信号，要我们驶向路边停靠。

《牛津词典》

The police car was gaining ground on the suspects.

警车渐渐逼近犯罪嫌疑人。

《牛津词典》

A newspaper may report, for example, that police have arrested the suspected kingpin of a car-stealing operation.

VOA: special.2009.11.29

In the case of the ambulance and police car, it's more a question of brightness.

警车和救护车上之所以用红灯，大多是因为红灯亮度大。

耶鲁公开课 - 文学理论导论课程节选

Moscow police detained several protesters, but they are not the ones who should be arrested, says car owners federation head Sergei Kanayev.

VOA: standard.2010.05.19

McManus admitted dangerous driving, hitting the police car and Mr Sadiq to his severe injury.

BBC: Drink-driver Patrick McManus jailed for nine months

He and a big deputy stepped out of the police car and walked to the roadside fence.

NEWYORKER: Idols

Avon and Somerset Police have referred the collision to the Independent Police Complaints Commission because of the involvement of the police car.

BBC: NEWS | UK | England | Somerset | Inquiry after police chase death