A driver has died in a serious accident on Derry Hill near Chippenham involving an overturned lorry and two cars.
The accident happened just before 0800 BST on Thursday, between the Saab Garage and the Lysley Arms pub.
A car is believed to have crossed the carriageway and crashed head-on into the lorry.
Two fire crews attended and the junction, of the A4 with the A432, is expected to be closed until at least 1300 BST.
Two other people have been taken to local hospitals.
As a result, Stagecoach buses which run between Swindon and Chippenham will terminate at Calne.