A Greater Manchester Police officer has been found guilty of careless driving after a crash which injured five people, one seriously.
PC Daniel Aimson, 31, was given an absolute discharge at Preston Crown Court.
An investigation found he drove at 73mph in a 30mph zone and drove through a set of traffic lights showing red before the collision in Leigh in November 2011.
He was cleared of dangerous driving.
He had denied careless driving but was convicted by a jury. Judge Robert Altham cited "special reasons" on granting the PC, who is based at Swinton Police Station, an absolute discharge.
Greater Manchester Police referred the case to the Independent Police Complaints Commission (IPCC) which carried out an investigation into the crash.
The watchdog found the PC was driving a marked police car along King Street, Leigh when he spotted a car travelling in the other direction and the driver was not wearing a seat belt.
The IPCC said he turned his car around with the intention of stopping the car and accelerated to a speed of 73mph.
He slowed to 64mph before going through traffic lights which were on red at the junction of Lord Street and Spinning Jenny Way, when he crashed into two vehicles and caused one to collide with a third, the IPCC said.
One man sustained serious injuries requiring surgery while four other people received minor injuries.
The police car's blue warning lights were on but the siren was not activated when the crash happened, the IPCC found.
IPCC commissioner James Dipple-Johnstone said: "Although PC Aimson was a highly trained police driver our investigation showed his actions on this day were careless.
"His failure to activate his siren meant the other road users had no warning of his approach and his decision to go through a red light at such high speed was a shocking error.
"It is only through good fortune that we were not investigating a death."