CLEVELAND – The brother of a high school student who shot and wounded four people before killing himself was led out of his home in handcuffs by police officers on Thursday, as family members looked on and called his name.

Officers placed Stephen Coon in the back of an unmarked car, then several officers went into the house. It was unclear why Coon was being taken into custody.

“Please have respect, I just lost my brother,” Coon said as he was being escorted from the house.

Asa Coon, wearing a Marilyn Manson shirt, black jeans and black nail polish, opened fire with two revolvers on Wednesday, wounding two students and two teachers at SuccessTech Academy in downtown Cleveland. He had a history of mental problems and was known for cursing at teachers and bickering with students.

A classmate said Thursday that he and others had warned their principal about threats by Asa Coon and said the attack could have been prevented.

The student, Rasheem Smith, said on CBS’ “Early Show” that despite their warnings, principal Johneita Durant told them she was too busy.

“I told my friends in the class that he had a gun and stuff,” said Smith, 15. “He was talking about doing it last week. I don’t know why they didn’t say nothing.

“We talked to the principal. She would try to get us all in the office, but it would always be too busy for it to happen,” Smith said.

Responding on the show, schools CEO Eugene Sanders said the district would investigate. “We’re going to review the entire situation over the course of today and tomorrow, make a determination of what has indeed occurred, and then see what the appropriate recommendations are, so we can move forward on Monday morning,” he said.

A message left at Durant’s office was not returned. A phone call to her home was not answered.

All classes in the city school district were canceled Thursday, and counseling was to be available for students.

Coon, who was suspended Monday for fighting with a classmate and was under suspension at the time of the shootings, had warned classmates of an attack, but none took him seriously.

“When he got suspended, he was like ‘I got something for you all,'” said student Frances Henderson, who said she often got into arguments with Coon. “I guess this is what he had.”

Coon, who was white, stood out in the predominantly black school for dressing in a goth style, wearing a black trench coat, black boots, a dog collar and chains, she said.

Henderson, who is black, she said she didn’t believe race played a role in the shootings.

“He’s crazy. He threatened to blow up our school. He threatened to stab everybody,” said Doneisha LeVert, 14. “We didn’t think nothing of it.”

On Thursday, a spokeswoman said Sanders will give the Mayor Frank Jackson a plan by Friday at noon to address whether additional security measures are needed at the school and how the school identifies potential problems among students.

Police Chief Michael McGrath said Thursday that the preliminary investigation found that Coon entered the school and went to a fourth-floor bathroom, where he changed clothes and took items out of a duffel bag, possibly the weapons, and put them on his body. There was an armed security guard at the school’s entrance, McGrath said, though it was not known how Coon got inside.

McGrath said Coon went to a specific classroom and shot the teacher and then, while looking for a second teacher, he fired some other shots, wounding another teacher who was trying to help students go to another floor, he said.

After the shootings, police found the guns: a .22- and a .38-caliber revolver, McGrath said. He also had a box of ammunition for each and three tactical folding knives.

McGrath said the guns are older, meaning it will take some time to trace them. He said officials would be talking to Coon’s older brother and mother about the weapons.

Coon’s troubles seemed to come to a breaking point this week. Students said Monday’s fight was over God – Coon told his classmates he didn’t believe in God and instead worshipped rocker Marilyn Manson.

McGrath said that since 2006, police had gone to Coon’s home five times: for calls about domestic violence, an assault call, a property crime and a hit-and-run accident.

Coon had spent time in two juvenile facilities and threatened to commit suicide while in a mental health facility, according to juvenile court records obtained by The Plain Dealer newspaper.

When he was 12, Coon was charged in juvenile court with domestic violence. His mother, Lori, had called police and told them her son slapped her and called her a vulgar name. She had been trying to intervene in a fight between Coon and his twin sister, The Plain Dealer reported.

He was also suspended from school last year for attempting to hurt a student, the newspaper said. “He used to cuss all the teachers out,” said Henderson, 14.

The first person shot, 14-year-old Michael Peek, had punched Coon in the face right before the shootings began, Smith said.

Coon “came out of the bathroom and bumped Mike and he (Mike) punched him in his face. Mike started walking. He shot Mike in the side,” said Smith.

Darnell Rodgers, 18, said he realized he had been shot when he felt his arm burning.

Rodgers was treated for a graze wound to his right elbow. He told NBC’s “Today” on Thursday he didn’t believe he was targeted.

“He just fired the gun,” Rodgers said. “He didn’t say anything.”

Michael Grassie, a 42-year-old history teacher, underwent surgery Wednesday and remained in the hospital Thursday, and an official said his prognosis was very good.

Math teacher David Kachadourian, who was treated for a minor wound to the back of one shoulder, knew of no reason why Coon would target him.

“I never felt personally threatened or personally at risk,” said Kachadourian, who had Coon is his beginning algebra class.

SuccessTech Academy, with about 240 students, is an alternative high school in the public school district that stresses technology and entrepreneurship.