Two casualties have been airlifted to the Southern General Hospital, with a further casualty taken by ambulance to the Dumfries and Galloway Royal Infirmary.
The Northbound carraigeway is closed and will remain so for a considerable period while investigations are carried out. The Southbound carriageway has one lane now re-opened.
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The driver of a Rangers supporters' bus which crashed on a roundabout killing a fan blamed the brakes when he was interviewed by police.
Sandy Murray, of Police Scotland, was was giving evidence at the trial of a bus driver who denies killing Ryan Baird by dangerous driving.
34-year-old Christopher Peck was involved in a head-on crash with a drunk driver. His funeral has taken place in his hometown, Workington.