The families are receiving support, according to a statement from Thames Valley Police on Twitter.
Two women have been killed in a crash involving the car they were in and a police car.
The incident has been referred to the Independent Office for Police Conduct (IOPC) for review.
Police shut the road for several hours following the crash.
The collision, which killed both the driver and passenger happened on the A4 Bath Road in the Calcot area of Reading, Berkshire, about 16:00 GMT on Tuesday.