GREEN BAY, Wis. -- Two 17-year-olds suspected of plotting a shooting spree at their high school were fascinated with the mass killings at Columbine High School and had homemade bombs and weapons at their homes, investigators said Friday.

The boys were arrested Thursday at East High School after a student went to an associate principal.

"If someone hadn't come forward, we'd be talking about funerals instead of charges," said Brown County District Attorney John Zakowski.

William C. Cornell and Shawn R. Sturtz were arrested for suspicion of conspiracy to commit first-degree intentional homicide and conspiracy to commit arson. They were expected in court later Friday for a bond hearing.

Police found nine rifles and shotguns, a handgun, about 20 "crudely made" explosive devices, camouflage clothing, gas masks, two-way radios and hundreds of rounds of ammunition at Cornell's house, Police Capt. Lisa Sterr said. She said Cornell had made several of the improvised explosive devices about two months ago.

At Sturtz's home, police found knives and ammunition, Sterr said.

Police said they also found mannequin heads that appeared to have been used for target practice, and suicide notes.

No dangerous materials were found at the school, Sterr said.

The two teens had long been fascinated by the April 1999 Columbine massacre in Littleton, Colo., in which two students armed with guns, knives and bombs killed 12 classmates and a teacher before killing themselves, Sterr said.

In Montreal on Wednesday, an attacker killed a student at Dawson College and wounded 20 others before killing himself. Kimveer Gill, 25, had dressed in a black trench coat like the Columbine shooters, posted online photos of himself with weapons and said he liked to play an Internet role game about the Columbine killings.

Sturtz was described as being obsessed with pain and death, and both he and Cornell had been described as being depressed over the last couple of years and hating school, according to Sterr.

Sturtz had also just lost an Internet relationship with a girl, Sterr said.

"Sturtz was very upset about this and became extremely enraged and (Wednesday) talked of soon attacking the school like Columbine," Sterr said.

Police Detective Tom Molitor said the two just needed a triggering event to pull off their plan.

"They were one bad day away from something happening. It could have happened yesterday," he said.

Asked whether the two were cooperating with investigators, Molitor declined to comment other than to say they have gathered details from credible sources.

"I believe there probably were other people who knew about it. It was very good luck that this person came forward," Molitor said.

The student who alerted school officials to the two teens was "shook up," school Superintendent Dan Nerad said.

Mayor Jim Schmitt praised that student as a hero.

Jason Burdick, 18, said he considered both teens friends. He described Sturtz as a "teddy bear" and a shy, quite kid.

"He was nice to get along with. No fights or whatever," he said. "But he, like, turned."

Burdick said Sturtz started watching documentaries and other programs about Columbine.

"I think that is what kind of turned him," he said. "I didn't think anything of it. He just kind of joked around with it. You know, just talking."

Burdick said he played war games once with Sturtz with BB guns.

"I went over there one night and we had like little battles," he said. "It was just like a fun little sport."

He said people sometimes made fun of Sturtz for having a chin beard, teasing him that it looked like a helmet strap.

Felicia LaPere, 17, said Sturtz had a darker side and was into Goth culture.

"But there was nothing suspicious about him that you would think he would try to do something like this," she said.

She said she was shocked that Cornell would be involved in such a horrendous plot.

"He seemed very in control about what he was doing and who he was," she said.