A tractor trailer carrying milk caught on fire on Wednesday afternoon in the northbound lanes of I-476, shutting down the traffic in those lanes for nearly an hour, according to Lt. Matthew O'Brien with Centre Square Fire Company.

The driver of the rig was able to exit the vehicle to safety and was uninjured in the one-vehicle incident.

Firefighters are unable to determine the cause of the fire at this time.

O'Brien said that truck crews from Centre Square and Harmonville responded to the vehicle fire, but took an extended amount of time to reach the scene due to traffic on the turnpike. However, Centre Square's ladder truck, Tower 33, found a faster route to the scene and made its first appearance at a turnpike vehicle fire.

Because the turnpike in this area is under construction, the shoulder is all dirt, which was beneficial so no brush caught on fire, he said.

O'Brien also told Patch that there was a vehicle fire on Tuesday in the same area in the southbound lanes. However, he said the two incidents are coincidental.

Original story follows:

A tractor trailer traveling northbound on I-476 burst into flames shortly before 4:30 p.m. today, shutting down traffic approximately two miles north of the Mid-County Interchange.

Firefighters from Harmonville and Centre Square Fire Companies responded and said the flames were under control by about 4:45 p.m. and that the driver escaped unharmed.

What caused the fire is currently unknown, but firefighters said there were no other cars involved. The fire quickly burnt through the vehicle, leaving little left of its cabin.

The incident took place just behind an Aetna building in Whitpain Township, which was cleared because of the heavy smoke. A Patch reader on Facebook, who says that she works at a nearby business, said that they felt and heard an explosion, equating it to an earthquake.

Patch currently has calls out to authorities to learn more about what caused the fire and will update this story as we receive responses.

The northbound lane remains closed as of the last updating of this article at 4:56 p.m.