Police were called to Preston New Road at Clifton, between Preston and Freckleton, at 10.15am after getting reports of a crash between a van and a car.
Lancashire Police's Force Incident Manager Dave Britton said: "The van has hit [the car] and the driver has gone into some trees."
He added that the incident is still causing obstructions and the car is badly damaged.
The driver of the car, a woman, has been taken to hospital as a precautionary measure. The extent of her injuries are not known.
Police are now looking to find a Beagle dog called Ollie that ran away from the scene after leaving the woman's car in the aftermath of the crash.
A spokesman from Lancashire Road Police said: "We are currently dealing with a collision on Preston New Road at Clifton.
"A Beagle dog has ran away from one of the vehicles involved. He was last seen running across fields towards Clifton village.
"Dog is named Ollie. Please share and help us find him!"
Anyone with any information on the crash or Ollie's whereabouts can contact police on 101 quoting log reference 495.