An autopsy has determined that a 28-year-old Hilo man who was involved in a head-on collision with another vehicle Saturday died of natural causes, and not from injuries sustained in the collision.

Kimo K. Elderts was involved in the two-vehicle crash on Queen Ka'ahumanu Highway, three-tenths of a mile south of the 71-mile marker, shortly after 1 a.m. Saturday.

Two compact cars collided head-on. The two people in the other vehicle were hospitalized at North Hawai'i Community Hospital in serious condition, Big Island traffic investigators said.