STROUD, Okla. (AP) — An Oklahoma Highway Patrol trooper fatally shot the driver of a semi truck during a traffic stop Wednesday morning on Interstate 44, the patrol said.

The trooper shot the man near a toll booth east of Stroud, about 55 miles (88.5 kilometers) east of Oklahoma City and about halfway between Oklahoma City and Tulsa, OHP spokesperson Sarah Stewart said.

The names of the trooper and the man were not immediately released. Stewart said there were no other injuries as a result of the shooting.

The trooper had stopped the driver for a traffic violation on the interstate, also known as the Turner Turnpike, Stewart said.

“Some sort of altercation” began between the two and the trooper opened fire, Stewart said. “We’re still trying to figure everything out” and investigators were still at the scene about noon Wednesday.

Stewart declined to say if any weapons were found on the man, citing the ongoing investigation.