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 Tuesday night after someone tipped off police about the plot.
Castor told a news conference that police and the school system "were probably able to thwart a potentially catastrophic event, the likes of which the city of Tampa has not seen, and hopefully never will."
At Cano's 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.
Castor said the minute-by-minute plan to bomb the school included his intent to cause more casualties than the 1999 Columbine High School massacre that resulted in the deaths of 13 people before the two shooters killed themselves.
The plot targeted specific school administrators and any students who were nearby, police said. They did not name the administrators. They also would not disclose who tipped them off about the plot.
Cano's mother consented to a police search at about 6:30 p.m. Tuesday, Castor said. In addition to the bomb-making materials, police also found a marijuana growing operation.
Cano 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 had 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.
Police Maj. John Newman said Cano had been on a list of juveniles who police checked on from time to time because of their brushes with the law.
"We've been very, very familiar with him," Newman said.
The St. Petersburg Times reported that prosecutors, at a hearing Wednesday morning, said that when Cano was arrested he repeated his plan to discharge a bomb and cause mass casualties at the school.
The Times reported that Cano tried to speak when he appeared before a judge Wednesday morning but was quickly hushed by a public defender standing next to him.
"The plot wasn't..." Cano said, before the public defender stopped him and told the judge that "he has no comment," according to the Times.
Cano was expelled from Freedom High School in April 2010 because of an off-campus incident that was not school-related, Hillsborough County schools spokeswoman Linda Cobbe said.
Last year, he attended a charter school and left voluntarily in March, Cobbe said. At that point he was 16 and could have chosen to drop out. He was not registered to attend classes this upcoming school year.
"We're thankful to Tampa police for taking the tip they got seriously and working with us to keep our schools safe," Cobbe said.
Cano's Facebook page includes photos of him holding a machete and drinking from a bottle of malt liquor. He says he attends the "University of Marijuana," where he is studying "how to grow weed."
He lists two favorite quotes: "lessons not learned in blood are soon forgotten" and "dont trust anybody, cuz they all just wait for you to s--- a brick of gold so they can take it." He only listed 25 friends.
Associated Press writer Christine Armario contributed from Miami.