Nineteen Polish illegal workers are to be deported after being arrested following a crash between a BMW convertible and a green double-decker bus.
Police dogs, a helicopter and patrol cars sped to the scene after passers-by reported seeing about 40 people running away from the bus and a Ford Transit van parked nearby, in Wokingham on Sunday afternoon.
Eleven women, aged between 20 and 49, and six men, aged 21 to 42, were arrested on suspicion of being illegal immigrants.
Details of the remaining two detainees have not yet been released.
A number of the men and woman, who were workers on a Slough farm, were put on flights back to Poland on Tuesday, Thames Valley Police said.
The remainder have been served deportation papers and will be sent to a holding centre until they are returned home, the force added.
A search continued until about 1600 BST on Sunday for the other suspected illegal immigrants seen running away from the crash scene, but none were found.
The driver of the BMW, which ended up in a ditch off the A321 Twyford Road, was freed by firefighters and treated at the scene by paramedics for minor injuries.