Lancashire Police want to speak to witnesses and are seeking the driver of a vehicle the serious collision on the M65 yesterday afternoon (Sunday, May 30).
The crash happened at around 4:50pm near to junction 5 on the eastbound carriageway when the driver of a Toyota Prius collided with the back of a horse box.
Officers said it is believed the driver of the Prius travelled into the same lane as the horsebox to avoid a small black vehicle, which had cut in front of it as the motorway goes from three lanes to two.
The Prius driver – a 69-year-old man from Blackburn suffered minor injuries, however, the passenger – a 63-year-old Blackburn woman – suffered a serious arm injury and remains in hospital.
No horses were injured in the incident.
The small black car did not stop and officers are 'urgently' trying to trace it.
Investigating officer, Sgt Dave Hurst, said: “We need to find the vehicle involved, which we believe to be small and black, so we can speak to the driver.
“If you know who this is or you saw what happened, and you know the make and model of this car, please get in touch. Similarly, if you have any dash cam footage of this incident, we need to speak to you.
“Lastly, I am appealing to the driver of the car to do the right thing and come forward. It may be that you didn’t realise what had happened and so please contact the police as soon as possible.”
Anyone with information is asked to call 101 quoting incident reference 1193 of May 30.
Alternatively, independent charity Crimestoppers can be reached on 0800 555111 or online at crimestoppers-uk.org.