Emergency services including the air ambulance have been dealing with a serious crash on the M74.
Police said they were called to a report of a crash believed to involve one vehicle near junction 20 northbound at around 4.45pm on Wednesday.
The Scottish Ambulance Service, fire service and the air ambulance also went to the scene.
Traffic Scotland tweeted at 9.30pm that the road remained closed.
A Scottish Fire and Rescue Service spokeswoman said: “We were alerted at 4.42pm on Wednesday to a report of a road traffic collision involving one vehicle on the M74 northbound between junctions 20 and 19 near Ecclefechan in Dumfries and Galloway.
“Operations control sent five appliances and special resources to the scene where crew remain in attendance.”
There was no information available about whether there were any casualties.
Some people travelling on the route took to social media to describe being stuck in traffic for several hours.
Sarra Hoy, wife of Olympian Sir Chris Hoy, tweeted: “Standstill M74 northbound, near Gretna, after what seems to be a dreadful accident. Not moving anytime soon.
“Lost track of the number of emergency vehicles we have seen and now air ambulance. Hoping everyone ok and so thankful for our incredible emergency services.”
She later added: “Going to be turned round shortly after almost four hours at a standstill. A huge operation.
“Thank you @policescotland and everyone involved. Praying and hoping for those involved in the accident.”
Meanwhile locals from nearby village Kirkpatrick-Fleming brought food, drink and ice lollies to people stranded in the traffic.
Stephen Muir, 38, said: “I delivered about 100 ice lollies, about 150 bottles of water, juice, apples, crisps donated by people within the village and local businesses.
“I am the chairman of the community council and we are a close community, (we) like to help each other.
“I work all over the country and have been stuck in many accidents with no food or anything to drink.
“From my house (I) could see a few children standing outside the vehicles with parents. It was 26C outside so felt it’s only right to go and offer help.”