PORTLAND, Ore. (KOIN) — A head-on crash between a sedan and a motorhome left 4 people dead on Highway 18 in Yamhill County, the Oregon State Police said.

The crash near milepost 49 happened around 11:30 a.m. A westbound gray sedan crossed the centerline and slammed head-on into the motorhome. Both vehicles burst into flames, officials said.

All 4 people in the sedan died at the scene. Their names have not yet been released. The 67-year-old Canadian driver of the motorhome and his passenger were not hurt, authorities said.

It’s not clear why the sedan crossed the line and hit the motorhome. OSP said the investigation is ongoing.