(CNN) Galveston County Sheriff Henry Trochesset said Monday he doesn't believe any of the victims killed Friday at Santa Fe High School were shot by officers during the crossfire with the suspected shooter.

The sheriff said the two school resource officers, who arrived at the school about four minutes after the shooting started and engaged the suspected shooter, were "heroes." Their actions enabled other officers to arrive and evacuate teachers, administrators and students, Trochesset told reporters.

Trouchesset said officers exchanged gunfire with the suspected shooter and negotiated with him for a 25-minute-span before he surrendered. The suspect and officers did not exchange gunfire that entire time, the sheriff said. At one point, officers were talking to the suspect from the hallway as he was in the classroom, the sheriff said

The sheriff said, "there were minimal shots fired, at least from us, from law enforcement" during the exchange.

"From what I see, I don't believe any of the individuals that were killed" were shot law enforcement during the crossfire with the suspect, Trochesset said.

Trochesset said authorities are waiting for the medical examiner's autopsies to be sure, and video footage from the school will help piece the timeline together.

Eight students and two teachers were killed. The suspect was taken into custody.

Texas governor to convene discussions on gun violence

Mass shooting hits home for sheriff

Trochesset said the officers, who arrived at the school's art lab section within about four minutes of the start of the shooting, exchanged gunfire with the suspect from the hallway; the suspected shooter was in a classroom, the sheriff said.

"They contained him in that one area, isolated to them, engaging with them, so he did no more damage to other classes," the sheriff said.

As "other heroes" arrived and ran toward the gunfire, students and teachers ran from the gunfire, he said.

"In every door they opened, they weren't sure what was on the other side of it, but they opened those doors continuously, time after time, until that school was cleared," the sheriff said.

The sheriff said the tragedy hit home for him. He said his granddaughter, a student at the school, was three doors down from where the shooting occurred.

"Anybody wants to hear their heart stop and see how long they cannot breathe, wait till that phone call comes in, until you know they're safe," he said.

He added: "And her best friend that spent the night at my house, swam in my pool, is dead from a tragedy."

Weapons used in the shooting

Authorities have identified the gunman as Dimitrios Pagourtzis, 17. He was armed with a sawed-off shotgun and a .38 caliber handgun, according to Texas Gov. Greg Abbott.

Last week, Abbott said that his information was that the guns were obtained from the suspect's father. However, a law enforcement official told CNN that authorities are still trying to determine whether the shooter got the two guns from his father.

Sawed-off shotguns are illegal without a permit from the Bureau of Alcohol, Tobacco, Firearms and Explosives. The .38 caliber handgun was purchased in the early 1990s, the official said.

Investigators have identified the original buyers, but how the weapons moved from them to the shooter is still being determined, the official said.

The suspect told an investigator he acted alone and spared people he liked because he wanted his story told, according to a probable cause affidavit.

Trochesset said the suspect was on suicide watch in the Galveston County Jail on Monday.

Pagourtzis is being held without bail and is accused of capital murder of multiple people and aggravated assault on a public servant. He has not entered a plea.

The suspected shooter won't face the death penalty if he is convicted. Under Texas law, offenders who are under age 18 and charged with a capital offense face a maximum punishment of life in prison with the possibility of parole after 40 years.

The victims include a girl who rejected the suspect

One of the students killed, Shana Fisher, had rejected the suspect's advances for months, her mother Sadie Baze said. Finally, about a week ago, she stood up to him in the middle of class to proclaim she would not go out with him.

Baze said she believes the incident embarrassed the suspect so much that he targeted Shana. "One of the shotgun shells was for my daughter," she said.

Shana had turned 16 days earlier.

Another student killed, Jared Black, turned 17 last week and was supposed to have a birthday party Saturday.

The massacre also claimed the lives of students Sabika Sheikh, a Pakistani exchange student; Chris Stone; Angelique Ramirez; Christian Riley Garcia; Aaron Kyle McLeod; and Kimberly Vaughan. Teachers Glenda Ann Perkins and Cynthia Tisdale were also killed.

The people hospitalized included retired Houston police Officer John Barnes, who served as a resource officer at the school and confronted the gunman.

Santa Fe Independent School District Police Chief Walter Braun said Monday Barnes was in the intensive care unit after surgery.

"He's had ups and downs. Today was a down day, so we're still in prayer," Braun said.

On Wednesday, district teachers and support staff will return to school, the district said. All students will return May 29, the district said.