Emergency services including an air ambulance have been at the scene of a serious crash on the A74(M).
Police said they were called to a report of a collision on the northbound carriageway, near junction 20 for Eaglesfield, at 16:45 on Wednesday.
The Scottish Ambulance Service, fire service and the air ambulance also went to the scene.
It is believed that one vehicle was involved in the crash. There has been no information about any casualties.
The road was closed and some motorists said they had been at a standstill for several hours.
On Twitter former MSP Hugh Henry said he had been stuck in traffic north of Gretna for two and a half hours.
He was among those who raised concerns that families with young children and pets may not have access to water in the sweltering temperatures.
Traffic Scotland said it had raised the issue with the Police Scotland control room “as a matter of urgency”.
In a tweet at 19:05, the agency said the road was likely to remain closed for some time and traffic was being diverted via the B7076.