A toddler who plunged down a 500-foot-deep abandoned gold mine shaft near his home died immediately of severe head injuries, Gilpin County Coroner Richard Allen said Saturday.

Allen said Michael Ryan Mills, who would have been 2 years old on April 5, died about 2:45 p.m. Friday, minutes after he wandered out of his backyard and fell into the shaft."Death was immediate," Allen said. "The cause of death was massive head injuries due to blunt trauma from the fall."

The boy's body was recovered about 10:41 p.m. Friday, search coordinator John Rittenhouse said.

The toddler and his 21-year-old sister were playing in the backyard of their Central City home, 25 miles west of Denver, when the sister went inside to answer the phone, Rittenhouse said. The boy wandered off and fell into the mine, 100 yards behind the home, minutes later.