Two men have died in a road crash today, moments after their car was seen speeding through a town by a police officer.
The officer had lost sight of the Volkswagen Polo by the time it overturned and struck a tree in Bury, Greater Manchester Police (GMP) said.
The driver and a passenger, who have not yet been identified, were pronounced dead at the scene.
The crash happened at around 3.30am near Newbank Garden Centre on Bury Road in Radcliffe.
The area has been sealed off for forensic examinations. An officer from GMP's Professional Standards Branch was also in attendance.
The police driver will have his driving authority suspended, in line with standard procedure, while an investigation is carried out, the force said.
GMP said a taxi driver told them he was overtaken by the Polo, which was travelling at speed, moments before the smash.
A spokesman said: "At about 3.30am today an officer on routine patrol spotted a silver Volkswagen Polo with frosted windows travelling at excess speed along Bury Road, Radcliffe.
"The officer turned his car around and activated his emergency equipment to pursue the car but it had already driven off and the officer had lost sight of it.
"By the time he reached Newbank Garden Centre the car had overturned and collided with a tree.
"An independent witness - a taxi driver - has told police he was overtaken by the car, which was travelling at speed, moments earlier.
"The road has been closed and officers from the Serious Collision Investigation Unit are currently at the scene.
"An officer from GMP's Professional Standards Branch is also there.
"In line with standard procedure the driver will have his driving authority suspended while an investigation is carried out."
Superintendent Steve Nibloe added: "Tragically two men have died in this collision.
"They are yet to be identified or their relatives informed but we will have specially trained officers with their loved ones to support them as best we can as soon as we know who they are.
"Officers from our Serious Collision Investigation Unit are currently conducting enquiries at the scene and the road will remain shut while this happens.
"If anyone else has any information that may assist us I would urge them to contact us."
Anyone with information should call GMP on 101.