The A31 was closed for five hours between Sturminster Marshall and Bere Regis following a serious collision on Tuesday morning.
The incident happened near the A31/A35 junction in Bere Regis, and multiple emergency services attended just before 8am.
Dorset and Wiltshire Fire and Rescue services advised people to find alternative routes, whilst National Highways said Dorset Police, the Specialist Operations unit and the Ambulance service all responded.
DW Fire told Bournemouth One at the time: “Two crews are currently in attendance from Poole and Dorchester where they are working to remove one casualty from one of the vehicles. The road has been closed in both directions.”
Dorset Police added: “We received a report at 8.43am of a two vehicle collision on the A31 near Bere Regis, near to the turning to Winterborne Kingston.
“Officers have attended, along with the ambulance service and road closures have been put in place.
“At least two people are being treated by the ambulance service, we do not have an update on their condition at this time.
“We would like to thank members of the public for their patience and understanding while the road closures are in place.”