People at Coon's home declined to comment Wednesday evening.
Deberry's mother, Lakisha Deberry, said she was upset that metal detectors at the school were not always in use.
"You never know what's going on in someone's mind," said Deberry, adding that she was required to go through a metal detector and present an identification card whenever she wanted to drop off something at school for her children.
The shooting occurred across the street from the FBI office in downtown Cleveland, and students were being sent to the FBI site.
Classes at all schools in the Cleveland Metropolitan School District will be canceled Thursday, said Eugene Sanders, chief executive officer of the district. Counseling will be available Thursday for students at recreation centers throughout the city, Sanders said.
SuccessTech Academy is an alternative high school in the public school district that stresses technology and entrepreneurship. It is housed on several floors of the district's downtown Cleveland Lakeside Avenue administration building.
"It's a shining beacon for the Cleveland Metropolitan School system," said John Zitzner, founder and president of E City Cleveland, a nonprofit group aimed at teaching business skills to inner-city teens. "It's orderly, it's disciplined, it's calm, it's focused."
The school has about 240 students, most of them black, with a small number of white and Hispanic students.
Coon was white, and Henderson, the student who said she frequently argued with him, is black, but she said she didn't believe race played a role in the shootings.
The school, opened five years ago, ranks in the middle of the state's ratings for student performance. Its graduation rate is 94 percent, well above the district's rate of 55 percent.
Associated Press writers James Hannah, Terry Kinney, M.R. Kropko, John Seewer, Thomas J. Sheeran and Andrew Welsh-Huggins contributed to this report.