The scheme was stopped when two of the boys revealed the plan to Principal Barbara Boone. The Sunnyvale Department of Public Safety responded immediately. All 12 students were interviewed and taken into custody.

"They didn't want to hurt anybody, so they chose to commit the crime on Friday evening when everybody is home," said Capt. Glenn Fortin, public information officer of the Sunnyvale Department of Public Safety.

Nine of the students were arrested and suspended. Six of them were sent to juvenile hall, while three were cited and then released to their parents. The two boys who had gone to the principal and one other boy were released without being cited, according to Fortin.

The district attorney's office is still considering whether to charge the students with conspiracy to commit arson and vandalism.

Fortin said the parents of involved students cooperated with the investigation, including searches of their residences. The police didn't find any weapons.

Principal Boone said she was grateful the two boys came forward. "At their age, they want to conform. It took a lot of courage for them to tell us," Boone said.

To assure the parents of their children's safety, Boone wrote a newsletter to the parents, informing them of the incident.

"All participants made it clear that they only wanted to do damage to the school and had no intention of harming any of their fellow students," Boone wrote in the letter.

Neither the police nor the principal commented on why the students wanted to set the school on fire.