Two air ambulances, five ambulances and special operations teams were all called to the scene of the motorway near the village of Kirkpatrick-Fleming at around 5pm on Wednesday.
The conditions of those in hospital are not yet known.
The crash caused major traffic problems on the busy road, with drivers left stranded in cars for up to four hours while the road remained closed.
A spokeswoman for the Scottish Ambulance Service, said: “We received a call at 1710hrs on Wednesday 21 July 2021 to attend a road traffic collision on M74, northbound at Lockerbie.
“Multiple resources including five ambulances, three of our special operations resource teams, two trauma teams and two of our air ambulances were dispatched to the scene and seven patients were conveyed to hospitals.”
Thanks to those who helped out today on the M74. Some drivers giving out water to others & kind hearted residents of Kirkpatrick-Fleming went out of their way to help drivers and passengers. Thinking of those hurt in crash. Remarkable response from emergency services.
— Hugh Henry (@hughhenry_12) July 21, 2021
We told earlier how drivers, including former Scottish Labour MSP Hugh Henry, praised members of the nearby village who brought water and food as parts of the country soared to near-record temperatures.
It’s thought temperatures in the area was around 26C when people were stuck in traffic.
The former Renfrewshire South politician wrote online: “Stuck on the M74 north of Gretna for over two and a half hours.
“I’ve never seen so many emergency vehicles at one incident so it must be bad. I hope Traffic Scotland will liaise with Police Scotland to make sure anyone with young children gets access to water.”
He later added: “Thanks to those who helped out today on the M74.
“Some drivers giving out water to others & kind hearted residents of Kirkpatrick-Fleming went out of their way to help drivers and passengers.
“Thinking of those hurt in crash. Remarkable response from emergency services.”
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. ???????? pic.twitter.com/BPbYCztHyA
— Sarra Hoy (@SarraHoy) July 21, 2021
Stephen Muir, chairman of the village community council, was one of those who delivered essential items to those stuck on the motorway.
The 38-year-old 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.”
A Scottish Fire and Rescue Service spokeswoman said last night: “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.”
Police Scotland have been contacted for comment.