Madison police said they arrested a 16-year-old West High School student inside the school Monday morning after she attacked another student with a bicycle part.
Police said the victim, a 15-year-old girl, was hit several times in the head with a bike peg, which is a hollow 5-inch tube.
The victim was taken to a hospital, where she needed several staples to close a wound, according to a Madison Police Department incident report.
The suspect was angry with the victim because she believed the 15-year old recently stole her iPhone, police said.
The 16-year-old girl was taken to the Juvenile Reception Center on a tentative charge of substantial battery, according to the incident report.