A stretch of the A303 through Somerset has been closed this afternoon after a lorry overturned on a busy roundabout.
Emergency services were called to Sparkford, near Wincanton, shortly after 12.30pm to deal with the overturned lorry and a fuel spillage.
The road has been closed in a westbound direction between the A371 junction for Wincanton and the Hazelgrove Roundabout at Sparkford.
Police diversions have been put in place, while fire crews from Wincanton, Castle Cary and Yeovil were also at the scene.
A Devon and Somerset Fire and Rescue Service spokesman said: "Approximately 400 litres of diesel had spilt on to the highway. Crews requested the attendance of an incident support unit.
"Crews have stemmed the leak and are using absorbant granules provided by the Highways Agency. Advice was also sought from the Environment Agency regarding the spill."
The service said that nobody was trapped in the lorry when crews arrived, but details of any possible casualties are yet to be confirmed.
The Highways Agency said it does not expect the incident to be cleared, and the road reopened, until 6am tomorrow morning at the earliest.
Motorists have taken to Twitter this afternoon to vent their frustrations at the delays.
One user reported miles of queues, while another tweeted that it took 90 minutes to travel one mile.
It is the second lorry to overturn on an A303 roundabout in 48 hours.
On Monday afternoon, a lorry carrying a load of Ryvita crackers and crispbreads overturned on the roundabout at South Petherton.