TAMPA, Fla. >> Tampa police arrested an expelled student after thwarting what they called a “catastrophic” plot to set off a bomb at his former high school next week, they said today.

Police Chief Jane Castor said Jared Cano, 17, had threatened to plant a device at Freedom High School in north Tampa and discharge it on the first day of school Tuesday.

He was arrested last night after someone tipped off police about the plot.

At his home, police found materials to make pipe bombs, including a fuel source, shrapnel, plastic tubing and timing and fusing devices, Castor said. Police also found a journal containing schematic drawings of rooms inside the school and statements about his intent to kill.

They also found a marijuana growing operation in his home.

He faces felony charges of possessing bomb-making materials, threatening to throw, project, place or discharge a destructive device, cultivating marijuana, possession of drug paraphernalia and possession of marijuana.

Authorities said Cano has multiple juvenile arrests. Charges have included burglary, carrying a concealed weapon, altering serial numbers on a firearm and drug possession. All have been either dismissed or no action has been taken.

The St. Petersburg Times reported that prosecutors, at a hearing this morning, said that when Cano was arrested he repeated his plan to discharge a bomb and cause mass casualties at the school.

Cano was being held in secure detention.