The A45 has been closed eastbound near Northampton following a three-vehicle smash earlier today.
Emergency services rushed to the crash between Barnes Meadow and Riverside just before 2pm.
Queues were heading back to Wootton 90 minutes after the crash.
Northamptonshire Police reported earlier that a Nissan Micra, and Audi and a van were all involved in the pile-up.
Paramedics were treating a woman although police said her injuries were not believed to be life-treatening.
A Northamptonshire Police spokesman tweeted: "Motorists are being urged to avoid the A45 westbound in Northampton near Riverside.
"Fire crews are currently attending a road traffic collision at the scene, with queues already tailing back up to two miles.
"Please find alternative routes if you are able to."
Highways England have set up diversions via the Bedford Road to the A509 roundabout at Warrington and back towards Wellingborough.