PC Mark Driver was taken to Burnley General Hospital with wounds to the knee and hand.
A huge manhunt involving a police helicopter from West Yorkshire was launched for the two men, who later hijacked three vehicles in separate incidents to make their escape.
They held up a van outside Stoneyholme Post Office in Burnley and the police constable's vehicle was fired on in nearby Robinson Street. Police said the last of the cars hijacked by the robbers had been found abandoned in nearby Reedley.
The Royal Mail said later it was offering a pounds 15,000 reward for information leading to the arrest of the robbers.
PC Driver, 26, the father of two young children, was later in a 'stable' condition with serious shotgun wounds to his right knee. Lancashire Police said PC Driver and his colleague in the car, PC Paul Ogden, 31, were fortunate not to have been killed.
Police in south London were last night investigating possible Mafia links after an Italian restaurateur was shot dead.
Domenico Ranno, 38, known as 'Mimo', was shot through the head at his home in Helix Road, Brixton. A neighbour heard the shot just before noon and alerted Mr Ranno's wife Ina, who found the body.
Detective Superintendent Gordon King said: 'I am not going to rule out any possibility, be it Mafia or a drugs connection. These two are the most likely at this stage.'
Police appealed for anyone who could shed light on Mr Ranno's business dealings 'legitimate or otherwise' to contact them. Mrs Ranno was still being interviewed by detectives about her husband's business affairs.
There have been two recent attempts to break in to the house.Reuse content