A busy stretch of the A64 in North Yorkshire was closed for a few hours after a van carrying prisoners overturned.
Three prisoners suffered non-life threatening injuries in the accident, police said.
The prison van, operated by the G4 security company, collided with two other vehicles and crashed on the westbound dual carriageway near Tadcaster.
Nine prisoners, being taken from Hull to various jails across Yorkshire, were travelling in the van.
Six of the prisoners escaped unhurt and were taken back to the jail. The injured prisoners needed hospital treatment.
The driver of the van too sustained minor injuries. The occupants of the other vehicles were not hurt, police said.
The shutdown on the stretch, a busy commuter route between Leeds and York, led to a long tailback of vehicles.
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