A truck that was transporting toxic material caught alight on Townhill on Tuesday morning, leading to traffic on the N3 being backed up for kilometres.
The incident took place in the northbound lane near the Peter Brown Drive interchange.
Msunduzi municipal spokesperson Thobeka Mafumbatha said fire officers had realised that the material — sodium hydrosulphide — would become toxic in heat or when mixed with water.
ER24 paramedics at the scene said it appeared that the truck’s engine had caught alight.
Mafumbatha said: “The cab of the rig was alight and firefighters exercised extreme caution to extinguish the fire ... without wetting the product.”
“According to material safety data sheet, sodium hydrosulphide ... is corrosive, and presents a hazard to unprotected skin.”
Drizit Environmental general manager Chris Labuschagne said inhaling the chemical after it had reacted with heat or water could be fatal.
The fire and fumes were contained and no one was injured or harmed during the incident.