BRAZIL, Ind. (AP) _ A 13-year-old boy with a grudge against a girl at school was arrested Friday on suspicion of planting at least seven pipe bombs _ one of which exploded _ on two vehicles belonging to her parents.

The boy was taken out of his middle school by police and is scheduled to appear in juvenile court next week.

One pipe bomb had been attached to the mother's van and exploded Friday as she was driving, but she was not hurt. Police later found four more pipe bombs attached to her husband's vehicle at the couple's home.

The names of the family and the student were not released.

State Trooper David Kuhn said the couple told police several weeks ago that the boy was stalking the family. The stalking began after the couple's daughter told school officials the boy had brought a gun to school, Kuhn said.

School Superintendent Thomas Rohr said rumors that the boy had brought a gun to school were never confirmed.