A 58-year-old man was taken to hospital after collapsing behind the wheel of his car in Leyland and colliding into a heavy goods vehicle.
Traffic was moving slowly as three police cars and two ambulance crews attended the scene on Towngate at 1.30pm on August 9 after the black Mercedes ran into the back of a TNT delivery lorry.
The road was closed for about an hour and motorists were diverted from the road and nearby King Street back towards Tesco while the man was being treated.
One eyewitness, David Wilson of Lancashire Photography, whose shop looked out on the incident, said: “There was a lot of people in the area and they were concerned about the man.
“A passing ambulance was called to the scene whose occupant, a elderly lady who was on her way to Chorley hospital, was brought into my shop while they attended to the car driver.
“Another ambulance arrived later for the other lady to take her to hospital.”
A spokesman for Lancashire Constabulary said: “The local man suffered a cardiac arrest in his vehicle at Towngate and collided with the rear of a small goods vehicle.
“He has been transferred to the Cardiac Unit at Royal Preston Hospital where he is still in a serious condition.”
The man had no physical injuries and there was minor damage to the bonnet of his car.