Four people have been arrested after two cars were found abandoned in Marton, say police.
A 19-year-old man and a 20-year-old woman, both from Blackpool, and a 22-year-old woman from Poulton were arrested on suspicion of aggravated vehicle taking.
And a 21-year-old man from Blackpool was arrested on suspicion of aggravated vehicle taking and driving whilst unfit through drink/drugs.
The vehicles were discovered on Mythop Road at around 4.15am on May 17 after a car was reported to be on fire close to another car that had crashed into a tree.
A spokesman for Lancashire Police said: "We were called out to an incident where a car came off the road and hit a tree.
"It seems a car was already on fire in the road when the second car came and tried to avoid a collision with the burning car. It left the road and hit a tree.
"Two male occupants ran off from the vehicle. A female occupant was found with a shoulder injury near the car and was treated by paramedics."
Lancashire police notified firefighters to attend the incident.
Watch Manager Kevin Warwick said: "We arrived to find a car heavily involved in fire which was extinguished using a hose reel.
"There was also a road traffic accident where a car left the road as it tried to avoid the other burning car.
"The occupants of this car managed to get out unassisted and a girl with a shoulder injury was treated by paramedics."
"The fire is being treated as deliberate and an arson investigation has been launched."
Anybody with information can contact police on 101 quoting log reference 0143 of May 17.
All four suspects remain in custody.