Rescue services are at the A4 in Marlborough freeing a passenger trapped after the car in which she was travelling turned over on its roof.
Police say the car clipped a car parked on London Road and the momentum was enough to cause the first car to overturn, blocking the A4.
Officers say the driver was able to get out of the wreckage but his passenger, understood to be his wife, was trapped.
Two fire crews are on the scene and police say the victim's injuries are not thought to be serious. The operation to free the woman is complete.
The Wiltshire Air Ambulance landed in the nearby Elcot Lane recreation ground and, within this minute, has taken off.
Police are operating diversions along Elcot Lane and the unmade up Barnfield lane, but delays are inevitable