A Mesa, Arizona, police officer was killed in a motorcycle accident that occurred Monday (Aug. 14) while he was riding on Twisp-Carlton Road, Okanogan County Sheriff Frank Rogers said in a press release Tuesday (Aug. 15).

Kurt A. Carlson, 42, was riding with two other friends when the accident occurred at about 7:10 p.m., Rogers said. According to Rogers, Carlson apparently became separated from his companions. When they realized he was not behind them, the other two riders backtracked and found the accident scene in the vicinity of 887 Twisp-Carlton Road, Rogers said.

First responders found Carlson and his motorcycle, a Honda ST1300, in the Methow River, the sheriff said. Carlson was pronounced dead at the scene, according to the release.

“It appears that Carlson had lost control and left the road, and went down an embankment into the river,” Rogers said. “It is unknown what caused Carlson to leave the roadway, but there were no skid marks or any other vehicle involved in the collision.”

Rogers said the accident remains under investigation by the sheriff’s office and by Okanogan County Coroner Dave Rodriguez.