Train lines are blocked between Welwyn Garden City and London Kings Cross.
According to Great Northern, all train lines between Welwyn Garden City and London Kings Cross are currently blocked due to a problem which is currently under investigation.
All trains are currently at a standstill and it is not known when they will be running again.
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 The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.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