Pcs Matthew Blades, 37, and Tom Clough, 38, were killed in the crash near Middlesbrough.
Two police officers who died in a crash that killed five others in the early hours of Saturday morning have been named.
Pc Matthew Blades, 37, and Pc Tom Clough, 38, were killed when a Volkswagen Passat which was travelling the wrong way down the A66 near Middlesbrough collided with their marked police vehicle that was going in the right direction.
The Independent Office for Police Conduct (IOPC) opened an investigation into the circumstances leading to the crash at 3.39am in South Bank after a mandatory referral from Cleveland Police.
Officers from Cleveland Police spotted a suspicious vehicle and a pursuit began before the car travelled onto the A66 and collided with a police car, the watchdog said.
Chief Constable Victoria Fuller said it was an “incredibly sad day for Cleveland”.
“These were brave officers protecting our communities and serving our residents who didn’t return home to their families at the end of their shift,” she added.
Prime Minister Andy Burnham said he was “devastated” to hear about the crash.
