The road was cleared at 3.45pm. (Image: Archant)
Paramedics and police spent more than four hours dealing with a five-car pile-up on the A1(M) this morning.
There were long delays around Stevenage and Knebworth after the crash on the northbound carriageway of the motorway near Junction 6 for Welwyn at about 11am.
All the vehicles were recovered and the road was cleared by 3.45pm.
Ambulance crews treated nine people for slight injuries at the scene and took four of them to Lister Hospital with minor injuries.
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