A 16-year-old boy punched a 15-year-old girl on a Madison Metro bus, breaking the girl's nose, Madison police said.
It happened Tuesday afternoon as the bus was traveling in the 5300 block of Retana Drive on Madison's far east side.
The boy, with whom the victim is acquainted, delivered a single blow to the victim, who also suffered a head cut, according to a Madison Police Department incident report.
The teens had been arguing before the violence, police said.
The victim was taken to a hospital, where she needed multiple stitches to close the wound.
The boy was arrested and taken to the Juvenile Reception Center on tentative charges of substantial battery and disorderly conduct.