Around 30 firefighters tackled a large blaze on the roof of a office building in Breakspear Way, Hemel Hempstead this morning (Wednesday).
The fire broke out at about 09:10am, Hertfordshire Fire and Rescue Service said.
And five crews plus the aerial ladder attended and the fire was put out by 10:50am.
The A414 between junction eight on the M1 and Maylands Avenue was closed while emergency services dealt with the incident. It is now been reopened for traffic.
A police spokesman said: "Police were called at 9.12am this morning (Wednesday 3 July) to reports of a fire on the roof of a building in Breakspear Way, Hemel Hempstead.
"The fire service have brought the blaze under control. Thankfully no injuries have been reported.
"Enquires looking into the cause of the fire are to be carried out."
More to follow.