The unidentified girls -- two age 13 and the other 12 -- allegedly attacked Paola Neri around 7:50 a.m. Tuesday as she put her 8-year-old daughter, Melanie, on a school bus in New Windsor, N.Y., near Newburgh, about 65 miles north of New York City, police said.
The girls told police they were "mobbing" or "popping" on Neri just for fun, repeatedly kicking, punching and dragging the woman by the hair, Mid-Hudson News Network reported.
They said they chose their victim at random, the Middletown, N.Y., Times Herald-Record reported.
The woman suffered head and internal injuries, cuts and bruises all over her body, police said. She may have a concussion, WABC-TV, New York, reported.
Two of the girls were on their way to school and the other was suspended, police said. All three confessed, police said.
The girls were also charged with endangering the welfare of a child, Mid-Hudson News Network reported.
They were turned over to their parents pending an appearance in Orange County Family Court.