Florida police have thwarted a potentially "catastrophic" plot to set off a bomb at an expelled student's former high school.
Officers searched Cano's home on Tuesday, after a telephone tip, where they found several bomb components including fuel, shrapnel, plastic tubing, fuses and timing devices in his room, AP reports.
They also found a detailed "manifesto" with a minute-by-minute account of the plot, including layout drawings of where he would plant the bombs, and statements about Cano's intent to kill specific administrators and students.
"We were probably able to thwart a potentially catastrophic event the likes of which the city of Tampa has not seen and hopefully never will," local police chief Jane Castor told reporters on Wednesday.
The materials also "mentioned his desire to cause more casualties than were suffered at Columbine", Castor said, referring to the 1999 school attack in which two well-armed teenagers killed more than a dozen people in Colorado.
Cano faces felony charges of possessing bomb-making materials and threatening to throw, project, place or discharge a destructive device.
He also faced several charges relating to a marijuana-growing.
However, a friend said he was just "venting" his anger and would never have carried it off, ABC reports.
The unnamed friend was at the home of Cano when he was arrested on Tuesday.
"He wouldn't go and do something like that. He'd say he's going to in the heat of the moment but that's his way of venting, I guess," Cano's friend told ABC Action News in Tampa. "I think he was just venting anger on a piece of paper."
The two friends would often play video games at the home where Cano lives with his mother, and were planning to do just that on Tuesday when police arrived at the home to arrest the teenager, ABC reports.
The state attorney's office will decide if he will be charged as an adult, AP reports.
Cano had been arrested several times, most recently accused of breaking into a house and stealing a handgun, Tampa police said.
He had a court-ordered curfew and was on a police watch list.
"We've been very, very familiar with him," police Major John Newman said.
Administrators at Freedom High School said Cano had been expelled 18 months ago.
"I'm not sure his plot was realistic to carry out," principal Chris Farkas said at a news conference held at the school.
Police told Farkas that Cano worked alone.
Police said Cano's mother let them search the family's apartment in a modest complex just a few kilometers from the school.