Authorities say a 13-year-old girl is dead and her 12-year-old brother is missing after they became trapped in water near a dam on the Kankakee River in northeastern Illinois.

Police in Wilmington say the search for the boy resumed Tuesday morning. The Will County Coroner's Office identified his sister as Abiyail Arroyo of Joliet. She was pronounced dead Monday evening after being taken to a hospital in serious condition. An autopsy is scheduled for Tuesday.

Wilmington is about 60 miles southwest of Chicago.

Police Chief Phil Arnold says the siblings went into the water and two bystanders tried to help.

It wasn't immediately clear how the children ended up in the water. Friddle says the area is marked with "no swimming" signs.