FAIRFIELD (CBS SF) — A California Highway Patrol motorcycle officer and a motorist were killed Friday in a horrific accident during a traffic stop along Interstate 80 in Fairfield, authorities said.

CHP Golden Gate Division Chief Ernie Sanchez told reporters that CHP officer Kirk Griess — a 19-year veteran — and motorist he had pulled over were on the right shoulder of I-80 when another vehicle slammed into them.

CHP Officer Kirk Griess (Fairfield Police Dept.)

“He (officer Griess) was conducting an enforcement stop involving another vehicle, in this case it was a Saturn, (and) for unknown reasons the driver of a three-quarter ton pickup truck left the main portion of the roadway, traveled onto the shoulder and struck officer Griess…as well as the motorist who was still in the Saturn,” Sanchez said.

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Wrecked CHP motorcycle following a crash on Interstate 80 in Fairfield, August 10, 2018. (CBS)

Both of the injured were transported to a local hospital in Fairfield “where unfortunately, both passed away.”

The driver of the truck was also injured. Sanchez said he was being interviewed at the hospital and cooperating with investigators.

“It’s a tough day for the California Highway Patrol,” he said. “It’s a tough day for the state of California.”

The 46-year-old Griess, who’s a military veteran, is survived by his wife, Keri; adult daughters, Kadi and Kaci; and son, Kole, 14.

The driver of the SUV who was killed was identified as 49-year-old Jaime Bueza Manuel of Vallejo.