A fuel tanker went up in flames causing a road to be closed in both directions.
It happened shortly before midday on the southbound carriageway on the A21, near Lamberhurst.
At its height, six fire engines were at the scene.
Previous advice to keep windows and doors closed due to smoke is no longer in place but people are still advised to avoid the area where possible.
Nobody is believed to be injured.
Traffic was queuing from the A262 Forstal Farm Roundabout, near Tunbridge Wells, to the B2169 Scotney Castle Roundabout.
The road required resurfacing before it could be reopened and remained shut for several hours, reopening before this morning's rush-hour.
Diversions were set up through Lamberhurst via Spray Hill, High Street and School Hill.
A police spokesman said: "Kent Police was called at 11.45am today to a report that an HGV tanker was on fire at a location on the A21, near Lamberhurst.
"Officers are at the scene, assisting the Kent Fire and Rescue Service.
"There are no reported injuries and the road is currently closed in both directions."
A Highways England spokesman said: "The A21 is closed in both directions between the A262 and the B2169, near Lamberhurst, due to a vehicle fire.
"Emergency services are at the scene."
Tunbridge Wells Borough Council says some of its recycling and waste vehicles were caught up in the traffic jams and warned residents their collections could be disrupted as a result.
It urged people to leave their bins out as refuse workers would return for them as soon as they could.