Four lorries were destroyed in an arson attack at a fuel yard.
Essex Police are trying to trace a group of teenagers seen running away from the scene moments after the blaze started.
Twelve fire crews were called to put out the fire at West Station Yard in Maldon, Essex, at 6.40pm, an Essex Fire and Rescue spokeswoman said.
Divisional Officer Andy Stapleton said: "Crews worked excellently to prevent the fire from spreading to fuel storage tanks in the yard. The fire affected four lorries in the yard."
Police said that CCTV shows a boy running across the yard before and after the fire.
"We are obviously keen to identify him and would like parents and friends to help us with our enquiries," a police spokesman said.