The A505 is closed between Royston and Duxford after an overnight wood recycling plant fire.
Emergency services were called to an open fire at Bridge Foot Quarry, Flint Cross, near Melbourn, at about 10.20pm last night.
The fire involved a large quantity of wood chippings and was put under control. Cambridge Fire and Rescue remain on the scene.
At 12.30am the A505 was closed between the junction with the A10 and Junction 10 of the M11.
People are being advised to keep doors and windows closed.
More to follow.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here