LEHIGH COUNTY, Pa. (CBS) – The Pennsylvania Turnpike says it’s working with investigators at the National Transportation Safety Board after a man was killed by a falling metal conduit inside the Lehigh Tunnel. 

The accident happened last Wednesday evening inside the southbound lanes of the tunnel on the Turnpike’s Northeastern Extension.

Officials say a section of an electrical conduit fell from the tunnel’s roof and crashed through the truck’s windshield, striking the driver on the head and killing him.

The driver, 70-year-old Howard Sexton III, was a Raymour & Flanigan driver.

Investigators are looking into why the conduit detached from the ceiling.

The investigation will likely be completed by Feb. 28 and NTSB officials expect to release a preliminary report in two to four weeks.