Three people have been killed and 11 have been injured in a crash on the M40 in Buckinghamshire.
Up to eight vehicles were believed to have been involved in the collision, at Loudwater flyover, near High Wycombe.
The crash happened on the southbound carriageway between junctions four and three, but affected the whole road.
On Thursday evening police said the northbound carriageway of the M40 had re-opened and the southbound section was reopening later.
One casualty was airlifted to hospital and the other 10 taken by ambulance, police said.
Police said investigations into the collision, which happened at about 1040 BST, were ongoing, adding that it appeared a lorry had crossed the central reservation and collided with vehicles travelling the other way.
Insp Steve Bridges said: "We are especially interested in anyone who saw a white flatbed lorry loaded with blue pallets travelling northbound from the M25 to junction three at High Wycombe."