Authorities say a Northern California teenager has been arrested in the stabbing death of a 9-year-old boy who was a family friend.

Contra Costa County sheriff's spokesman Jimmy Lee says 18-year-old William Schultz was arrested Sunday afternoon after he showed up at a San Francisco Bay Area hospital, hours after the victim was stabbed to death in his home.

The Contra Costa Times reports (http://bayareane.ws/1GyLV1b) that Byron Unified School District Superintendent Debbie Burnett confirmed Jordon Almgren attended third grade at Timber Point Elementary School in Discovery Bay, a waterfront community along the banks of the Sacramento-San Joaquin River Delta.

Jordon was taken by a family member to an area hospital, where he was pronounced dead.

A motive has not been released.