The Millennium Middle School in Tamarac was evacuated Monday afternoon, WBFS-TV, Miami reported. Nearby Challenger Elementary School, where 250 children were in an after-school program, was also emptied with students from both schools taken to a swim center.
The boy, who has been charged with disrupting a school function, was brought in for questioning late Monday. ABC News said other students reported he had been boasting about leaving bombs in the school.
The Broward County Sheriff's Department said the device had fake sticks of dynamite and a timer.
The middle school was already locked down because of a robbery in the neighborhood when it was evacuated, WBFS said.