An Allentown man was killed in a tractor trailer accident Sunday night.

The crash happened around 9 p.m. on Route 33 northbound near mile marker 22 in Hamilton Twp., Monroe Co.

The rig, driven by 62-year-old Terry Allen Graul, veered off the left side of the roadway, and hit the guard rail in the center median, police said.

The truck veered to the right then back to the left where it hit the guard rail again, and came to rest on the left side of the road, according to police.

Graul was taken to Pocono Medical Center in East Stroudsburg, where he was pronounced dead a short time later.

The cause of death is unknown and an autopsy was scheduled for Monday.