Drivers are being advised to avoid the A148 near Holt following a collision.
Police and fire crews were called to the scene at 5.12pm.
Two cars collided on the eastbound carriageway of the Holt bypass, with one vehicle overturning.
Fire crews made the scene safe and there are thought to be no serious injuries.
Some traffic is building between the roundabout between the A148 and the B1110 and Hempstead Road.
Emergency services remain at the scene.
For up-to-date information about the county's roads, visit our LIVE Norfolk traffic map.
Join our Norfolk Travel Information group on Facebook for all the latest traffic news in Norfolk.
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 The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.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