The driver, a man in his 50s from Preston lost control of his Peugeot Bipper van which veered off the road and hit a wall in New Hall Lane at around 11.15am.
The van had been travelling away from Preston and towards Brockholes Brow and the M6 when it crashed into the perimeter wall of Preston Cemetery.
Emergency services rushed to the scene, near the Shell garage, and the man was taken to hospital.
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Lancashire Police said he remains in a serous condition. No other vehicles were involved and no other casualties have been reported.
New Hall Lane was closed for around three hours whilst police and ambulance crews worked at the scene.
A doctor working at Royal Preston Hospital's emergency department has praised police officers who were first on the scene for potentially saving the man's life.
The quick-thinking officers had given the man CPR and defibrillation and ensured his airway was clear before paramedics arrived.
The medic, who goes by the username 'Dr Mike' on twitter, said the enhanced first aid provided by the officers meant that his patient was "alive and stable" when he arrived at hospital.
Deputy chief constable Terry Woods has since responded to the doctors' praise, saying: "Thanks for feedback to @LancsPolice Dr Mike. I’m a massive believer in getting the team trained & equipped to deal with situations presented & what you say justifies our commitment to enhanced first aid for @LancsTacOps. Thanks to you & yours for all you do too."
The incident caused heavy congestion in both directions of the A59, with traffic building back to junction 31 (Samlesbury Interchange) of the M6.
Police are now appealing for information from those who might have witnessed the crash.
Sgt Finn Quainton, of Lancashire Constabulary’s Tac Ops, said: "A man is in a poorly condition following this collision and I would appeal for any witnesses or anyone with information to get in touch."
Anyone who can help should call police on 101 quoting log 0679 of May 18.
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