BOSTON — An employee of a Westport transportation company was killed Monday in a crash on the Massachusetts Turnpike.

Massachusetts State Police say the crash took place at around 1:30 p.m. when a tractor-trailer traveling east on Interstate 90 in Brighton began to sway with the truck moving from the middle lane to the left lane. The truck then rolled over onto the cement median barrier and continued to travel for a "significant distance," according to police.

The truck came to a stop with the cab on the eastbound side of the highway and the trailer rolled over onto the westbound lanes before Exit 20. The container had separated from the trailer came to rest across multiple westbound lanes.

The driver of the tractor-trailer, Sterling Hullett, 49, of Fort Worth, Texas, was pronounced dead at the scene. Hullett was an employee of R&D Transportation in Westport. The truck was registered out of Texas and the trailer had a Maine registration.

No other vehicles were involved in the crash and no other injuries were reported.

The cause of the crash remains under investigation by Massachusetts State Police.