Truck bursts into flames after multi-vehicle crash on PA Turnpike's Northeast Extension

MACUNGIE, Pennsylvania (WPVI) -- A tractor-trailer burst into flames after a crash on Friday morning in the northbound lanes of the Pennsylvania Turnpike's Northeast Extension (I-476).

The crash forced the closure of the northbound lanes for a large part of the day, but the lanes have since reopened.

The crash happened in a construction zone of the turnpike around 6 a.m. near Mill Race Road between Quakertown (Exit 44) and Lehigh Valley (Exit 56).

The crash involved a state trooper's vehicle, a tractor-trailer and a third vehicle.

Video from a viewer shows the tractor-trailer after it burst into flames along the roadway.

Authorities say a Pennsylvania State Police vehicle was parked in the right lane of a construction zone for safety patrol.

A crash truck equipped with an attenuator and directional sign was parked behind the state police vehicle.

Investigators say the driver of the tractor-trailer hit the attenuator, then hit the passenger side of the state police vehicle.

The truck then struck a directional sign board before finally stopping on the right shoulder of the highway where it caught fire.

Only minor injuries were reported.