The A6 in Lancashire is suffering from severe congestion after the road was shut in both directions at Bolton-le-Sands this morning.
The A6 remains partially blocked in both directions at St Michael's Lane after a large fire broke out at a neighbouring building at 4.17am.
Police closed the road to enable fire crews to tackle the blaze before reopening the Morecambe-bound side of the road to traffic at 7.30am.
Severe delays are expected to remain for some time as traffic is forced to use the opposite side of the road to get past.
A spokesman for Lancashire Fire and Rescue Service said: "Four fire engines from Bolton-le-Sands, Carnforth, Morecambe and Lancaster alongside the aerial ladder platform from Morecambe were called to a fire involving a single storey commercial building on Bye-Pass Road, Bolton-le-Sands.
"Firefighters used eight breathing apparatus, one jet, two hose reels and a ventilation unit to extinguish the fire.
"The cause of the fire is now under investigation."
There is currently a three-mile tailback of traffic in both directions, from the Crag Bank Road junction in Carnforth to the A5105 Coastal Road junction in Bolton-le-Sands.