Four people have been injured in a serious road accident.
The 26-year-old male passenger of a Ford Trasit van suffered serious injuries in the incident on the A17 at Heckington, near Sleaford.
The driver was airlifted to Queen's Medical Centre in Nottingham with serious head injuries.
The male driver of a Ford Fiesta was taken to the hospital by ambulance and his female passenger was taken to Lincoln County Hospital.
Police say both lanes of the road will be closed until at least 8pm.
Motorists are advised to avoid the area.
Emergency services were called at around 3pm following the crash at the turning for Burton Pedwardine.
Anyone who witnessed the collision or who saw the vehicles before the incident should contact the Collision Witness Hotline on 01522 558855.