A van alight on the A41 between Kings Langley and Hemel Hempstead is likely to cause traffic delays.
Fire crews from Kings Langley and Hemel Hempstead were called to attend the incident after reports were made at 11.40am.
The people in the van were able to get out and are now standing away from it.
Hertfordshire Constabulary is also at the scene.
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 The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.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