A 3-year-old disappeared with her nanny on the way to school Tuesday — and only returned some 15 hours later when the woman unexpectedly brought her back after midnight.

Little Gabriella Russo and her nanny Fatima Alexander were seen on surveillance video leaving the girl’s Battery Park City apartment building at about 9 a.m.

Gabriella was never dropped off at her school in Lower Manhattan and her father notified police. After hours of family agony and efforts by cops to find her, the nanny returned home with the little girl in tow at about 12:15 a.m.

Distraught family members started to scuffle with the nanny, who was taken into police custody.

The nanny was later charged with endangering the welfare of a child.

The family said Alexander worked with them for a decade and had no known medical issues.