A cement truck hauling a heavy load of powdered concrete crossed the center line and slammed almost head-on into a King County Sheriff’s patrol vehicle in Tukwila on Thursday morning, according to a sheriff’s spokesman.

The deputy, who is in his 30s, and the truck driver were both transported to Seattle’s Harborview Medical Center in stable condition and are expected to be OK, said sheriff’s Sgt. Ryan Abbott.

The deputy suffered a broken leg. The 49-year-old truck driver was evaluated at the hospital, then arrested on investigation of vehicular assault because troopers suspect he was impaired at the time of the wreck, Trooper Rick Johnson wrote on Twitter. The Washington State Patrol is investigating the collision.

According to Johnson, the fully-loaded truck came off the off-ramp from southbound Interstate 5 to Interurban Avenue South too quickly, crossed the center line and slammed into the deputy’s patrol vehicle.

Abbott said the deputy, who is assigned to Metro Transit, was driving south on Interurban Avenue South at 48th Avenue South when the truck plowed into his patrol SUV at 10:15 a.m. The crash, which toppled a traffic light and closed the roadway, left the deputy trapped inside his vehicle, he said. A section of the cement truck toppled over.

“The deputy was talking. He was in pretty good spirits but in pain,” Abbott said.