One lane is currently closed on the northbound carriageway between junctions 34 (A683, Lancaster) and 35 (A601, Carnforth).
All traffic was held until 7am, with all three lanes closed whilst fire crews worked at the scene.
But the closure has now been reduced to one lane, leading to heavy northbound traffic this morning.
National Highways say the lane closure is likely to be lifted by 10am.
More to follow...