UPDATE: Flames engulfed a semi on Interstate 24 early Friday morning, an 18-wheeler traveling eastbound in Marion County caught fire just before 6 a.m. ET.

The Tennessee Highway Patrol said the fire initially started around the tandem area of the truck.

Heavy smoke could be seen from miles, traffic was at a standstill while firefighters battled the blaze.

Lieutenant John Harmon said the cause of the fire is still undetermined but says it could've been a hot brake that exploded. THP said the driver of the semi made it out of the wreck unharmed.

"He was driving down the road and heard an explosion. I spoke with the trooper on scene and they really don't know what it could've been,” Lt. Harmon said.

THP, along with the Marion County Sheriff’s Office and Kimball Volunteer Fire Department responded to the scene. All eastbound lanes were closed for about an hour before crews were able to open one lane.

Just minutes after firefighters left the scene the fire came back. Channel 3 contacted authorities to alert them it reignited.

Firefighters responded back to the scene and hosed down hot spots. Kimball Volunteer Fire Chief Jeff Keef believes hot coals in between plywood reignited a small flame, which he said is common in semi fires.
TDOT and THP worked to remove the semi and haul away debris.

Lt. Harmon said the trailer was carrying electrical equipment. Right now, it's not clear if that load was connected to the explosion.

"To my knowledge there was no threat, as far as the environmental concern,” Lt. Harmon added.

All lanes of traffic reopened just before 9 a.m. ET.
Investigators are working to determine what caused the wreck, but say the tractor trailer is a total loss.

PREVIOUS STORY: Interstate 24 has partially re-opened to traffic.

Earlier Friday morning, Marion County Sheriff's Office and Tennessee Highway Patrol were investigating a tractor trailer fire. There has been no word of the driver's condition at this time.

Traffic is backed up for at least 2 miles eastbound. Drivers should expect congestion around the area near mile marker 149 until traffic flow returns to normal.

PREVIOUS STORY: I-24 eastbound lanes were shut down Friday morning due to a vehicle fire. Details are limited at this time. 

Tennessee Highway Patrol reports the incident is near mile marker 149. This is east of Monteagle, and near South Pittsburg.

Westbound traffic is not affected at this time. 

Stay with Channel 3 on air and online as this story develops.