The incident occurred at about 7.30am on the westbound carriageway between junction 20 and junction 18. Cambridgeshire police said the collision involved two lorries. Both drivers were treated for minor injuries. Queues stretch as far back as junction 21, at Brampton Hut, and the carriageway has been closed by Highways England to allow vehicle recovery to take place. Motorists are being advised to avoid the area.