A fire at an industrial estate which forced 1,000 people to leave their offices has been put out.
Police said materials in a skip may have caught fire
The fire was at Hollywell haulage company, a recycling facility in Maxted Close, Hemel Hempstead, Hertfordshire.
Roads around the premises were closed and buildings near to the scene of the blaze were evacuated.
At the height of the blaze eight crews and 40 firefighters worked at the scene with six crews remaining to dampen down the area, Herts fire and rescue said.
The fire was near to the Buncefield oil depot, which was the scene of an explosion in December 2005.
Police said it was thought that materials in a skip had caught fire. There were no injuries reported.
There were reports of a number of explosions, thought to be from aerosols, after the blaze started.
One witness, Edward Philips, told BBC News 24 he could see "thick black plumes of smoke rising above the business park".
"It seems very reminiscent of the fire two years ago and obviously very close in time as well," said Mr Philips.
"The plume is visible from quite some distance away on the motorway."