Police are hunting a teenage boy spotted on CCTV minutes before and after the attack at the Total Butler fuel depot, West Station Yard, off Spital Road, Maldon.
The footage shows a youth running from between two of the tankers which appear to glow and smoke.
A police spokesman said: "We are examining CCTV which does show 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."
Nobody was injured in the fire, and police Scene of Crime officers have been liaising with firefighters to establish the circumstances.
The blaze destroyed four tankers and came dangerously close to spreading to storage tanks backing on to houses, forcing families to be evacuated.
Anyone with information should contact police on 0300 333 4444 or call Crimestoppers anonymously on 0800 555 111.
More news and reaction on this story in this week's Chronicle.