Police are trying to trace the occupants of five sporty hatchback vehicles after a car smashed through a wall into the top floor of a house.
Two men were seriously injured when their red BMW lost control on the A30 in Basingstoke, Hampshire, hit a kerb and became airborne on Wednesday night.
A third man who was helped from the car after the accident left the scene and is being searched for by police.
They also want to find the occupants of five hatchback cars seen in the area.
It is thought they might have seen the BMW before the crash and can provide evidence as to how it was being driven.
The two injured men remain in hospital after the accident in Rainbow Close, Old Basing.
The residents of the house, the Harman family, escaped uninjured as they were asleep in another bedroom.
They have been told they will not be able to live in their home for at least two months and that it will have to be partially rebuilt.