A 4-year-old boy was killed when a three-tiered concrete birdbath he was clambering over in his back yard broke and fell on him, authorities said.

John Dutriz was pronounced dead of head injuries at the University of California, Irvine, Medical Center shortly after Friday's accident, police spokesman Lt. Mike White said."It just appears to be one of those tragic things that occur," White said.

The boy was climbing onto a birdbath when it "fell over and broke in two," said Rick McAnally, a spokesman for the Orange County coroner's office.

He landed on a concrete surface around the birdbath, and part of the lawn ornament landed on him, McAnally said.