EVERETT, Wash. (AP) — A Washington state trooper fatally shot a man with a hammer who had attacked state Department of Transportation workers along Interstate 5 north of Seattle, law enforcement officials said.

Around 4 p.m. Thursday, state patrol troopers responded to a report of a road rage incident on the shoulder of I-5 northbound in Everett, the Snohomish County Multiple Agency Response Team said in a news release. The team investigates police use of force incidents.

The driver of a vehicle started ramming a Department of Transportation contractor vehicle that had a lift operating over a slough with two contractors on board, investigators said.

The driver had a hammer and during an altercation with the workers and a trooper, the trooper fatally shot the driver, according to the news release. The driver died at the scene despite aid from law enforcement, the news release said.

One of the Department of Transportation contract workers was injured and expected to survive, investigators said.

The names of the trooper and the person who was shot and killed have not been released. The Snohomish County Medical Examiner’s Office was expected to confirm the driver’s identity, as well as the cause and manner of death.

It wasn’t clear exactly what led to the shooting, how many shots were fired or why the driver allegedly began ramming the vehicle.

Traffic was backed up for miles and into the night because of the incident.