A section of the M42 was closed today after a lorry carrying shotgun rounds and boxes of lighter fuel caught fire.
The vehicle was travelling on the northbound carriageway of the motorway near Bromsgrove, in Worcestershire, when the blaze began in the cab shortly before 10pm yesterday.
Five fire engines rushed to the scene when the fire spread to the trailer and the cartridges began to explode.
Alan Mackie, from Hereford and Worcester Fire Service, described the incident as "like fireworks night come early".
After taking expert guidance from a military advisor, firefighters set up a 300-metre exclusion zone around the lorry and allowed the fire to burn itself out.
The lorry was transporting a variety of goods on pallets, including boxes of shotgun cartridges and boxes of bottled lighter fuel.
The northbound carriageway of the M42 was expected to remain closed for some time between junction 1 and the junction with the M5 while workmen repair the fire-damaged road surface.
Mr Mackie said the fire service would be contacting the Road Haulage Association to express its concern that the driver of the lorry did not appear to know that he was transporting explosive material.