DRAKE, Colo. (AP) — Police say a Colorado toddler has been found dead after going missing from his house.

The Larimer County Sheriff's Office says the 23-month-old's mother woke Monday morning and found the boy was gone. The door to their home was open and the mother told police she last saw him 30 minutes earlier before they both fell asleep.

Police say they found the boy in a nearby river and couldn't revive him using CPR. The child's name has not been released.

Authorities say the county's coroner will determine the cause of the boy's death.