Two vans were left completely burnt out after one caught on fire in Dunstable, on Tuesday afternoon.
The van rolled down Luton road and into another van on a driveway, which also caught on fire. The police closed both lanes of the dual carriageway.
Kelly Martin, of Luton Road, witnessed the fire, she said: “I came out of Tesco and saw all the smoke, I realised it was a van on fire.
“I don’t know how but it suddenly drifted out into the middle of the road and sparks came firing out of it.
“Then it started rolling down the road towards the houses and ended up smashing into the post, it caught the van that was on the neighbours driveway and it set alight as well and it kept making explosions.”
Bedfordshire Fire and Rescue sent two fire engines to the scene, the Police and the Highways Agency also helped to divert traffic and clean up the mess.
No one was hurt during the incident but both vans were burnt out. It is not known how the original blaze started, the fire service is investigating.
Ms Martin added: “We all had to stay inside our houses, my son was crying and screaming because it kept exploding.”
A spokesperson for Etyres said: “We are looking into what started the fire, it looks like the fire may have caused the handbrake to fail.”