MILWAUKEE — The Milwaukee Police Department says it is "simply unacceptable" that a 4-year-old girl was left overnight in a van that police had requested to tow.

The department said in a statement Monday that it "does not take this incident lightly," and pledged to "take whatever steps are necessary to prevent this situation from ever happening again."

The girl's mother was arrested last week on suspicion of drunken driving. A 10-month-old baby was taken out of the van but the mother apparently didn't mention the girl. A tow lot operator heard the girl crying the next morning. She apparently was OK.

The Police Department says it is reviewing body camera, squad camera and other available video.

The girl's mother, 28-year-old Blair Springfield of Milwaukee, is charged with OWI and child neglect.