CHICAGO (CBS) — A babysitter has been arrested for endangering the life of a child by leaving the two-year-old alone and going home, Riverside police said.

The 20-year-old from Bolingbrook was hired for the babysitting job in the Riverside home while the child’s mother went out to celebrate a birthday.

Police said the babysitter left the toddler alone after midnight after she became frustrated and went home.

The mother is not cooperating with police, according to Chief Tom Weitzel.

The case is under investigation.