A lorry carrying aerosol cans caught fire, causing them to explode and forcing a stretch of M11 to be closed down.
Traffic was at a standstill in both directions on the busy motorway and motorists were advised to find alternative routes.
Firefighters tackled the blaze between junction eight for Stansted Airport in Essex and junction nine for Duxford in Cambridgeshire.
The slip road for the A11 was closed, Essex Police said following the dramatic incident on Wednesday evening.
Viv Higgins said she was driving just behind the lorry when suddenly it “burst into flames”.
“A truck burst into flames in front of us on the M11… We were the first car behind it,” she told the Standard.
“We were so fearful that the driver hadn't escaped, but just heard that he did. Such a relief.
“We were so close and scared... We could back up for a while as traffic had built up behind us.
She added: “The lorry was exploding the whole time. Really dramatic.”
Mrs Higgins said that, before police arrived on the scene, two lorry drivers drove in front of the blaze to stop motorists from approaching any further.
“Two lorry drivers drove in front of us to stop people trying to drive past it before the police came. Such a sensible thing to do really.”
The blaze broke out shortly before 5pm.
Essex Fire and Rescue Service station manager Dave Bond said the aerosol cans were "scattered across both side of the carriageway" following the explosion.
In its latest update, Essex Police said the northbound carriageway was unlikely to be reopened before midnight as the debris was still being cleared.
The southbound carriageway needs additional work from Highways England, so may not reopen before 8am on Thursday morning.
