A six vehicle crash has blocked one lane of the A1 northbound near Wansford.
The crash happened at about 3.10pm this afternoon.
A Cambridgeshire police spokesman said there had been no injuries reported, and work was starting to recover the vehicles.
One lane is open, but there are long delays, and motorists are advised to avoid the area.
The AA is reporting delays of over 25 minutes.
UPDATE The vehicles have now been recovered but long residual delays remain and are likely to through the evening rush hour