A fire that began in a steel fabrication factory at Glossop has caused up to $4 million of damage, after it spread to two neighbouring businesses.
Police and fire cause investigators believe the fire was sparked by an arsonist.
The blaze started in the Glossop Steel shop on the Old Sturt Highway, and within minutes spread next door to the neighbouring business, Upper Murray Case Supplies.
Fire crews were called to the fire just before 5.30 this morning and it took 60 fire fighters two hours to bring the flames under control.
Crews have warned residents nearby that there is smoke in the area from the treated pine that was burned in the fire.
The two businesses have been described as the 'lifeblood' of the riverland town.