SPARKS, Nev. — A student at a Nevada middle school opened fire on campus just before the starting bell Monday, wounding two boys and killing a teacher who was trying to protect other children, Sparks police and the victim’s family members said.

Twenty to thirty students witnessed the tragedy at Sparks Middle School that also left the lone suspected gunman dead, police said. It’s unclear whether the student committed suicide, but authorities say no shots were fired by law enforcement. Police said between 150 and 200 officers, including some from as far as 60 miles away, responded to the shooting.

Family members later identified the staff member who was killed as math teacher Michael Landsberry, 45.

“In my estimation, he is a hero. … We do know he was trying to intervene,” Reno Deputy Police Chief Tom Robinson said about the fallen staff member.

Landsberry was a military veteran who leaves behind a wife and two stepdaughters, said his sister-in-law Chanda Landsberry. She said she wasn’t surprised he stepped in to stop the rampage.

The motive isn’t yet known. Names of the suspect and victims haven’t yet been released.

“As you can imagine, the best description is chaos,” Robinson said. “It’s too early to say whether he was targeting people or going on an indiscriminate shooting spree.”

Students from the middle school and neighboring elementary school were evacuated to the nearby high school, and classes were canceled. The middle school will remain closed for the week.

At the evacuation center, parents comforted their children.

“We came flying down here to get our kids,” said Mike Fiorica, whose nephew attends the school. “… It’s really chaotic. You can imagine how parents are feeling. You don’t know if your kid’s OK.”

One of the students injured in the violence that erupted around 7:15 a.m. is out of surgery and the other is doing well, police said. They went on to say the shooting happened on the school’s campus and ended outside the school building itself.

“I was deeply saddened to learn of the horrific shooting at Sparks Middle School this morning,” Nevada Gov. Brian Sandoval said in a statement extending his thoughts and prayers to those affected.

About 700 students in 7th and 8th grades are enrolled at the school, located in a working class neighborhood.