The suspect allegedly packed two loaded guns, pointed one at the principal's head and ignited a standoff with the school resource officer.
He was eventually shot near an entrance to the school library — where several frightened students were huddled together in an emergency lockdown — after repeatedly asking where a fire alarm was located.
Thomas Richard Cowan, 62, last known address of 2060 Mountain View Road, Kingsport, was transported to the hospital by helicopter. Authorities say he died at about 10:10 a.m.
According to a student that attended a press conference on the incident, Cowan is the brother of a custodian at the school.
Sullivan County Sheriff Wayne Anderson confirmed a family member of Cowan works at Sullivan Central, 131 Shipley Ferry Road, and is being questioned about the incident. He is allegedly, "just as shocked as everyone else."
"There is no doubt in my mind that (Cowan) went there to kill somebody today," Anderson said. "We don't know who, we don't know why, but we'll find out."
Central dispatch received a call reporting a gunman in the school at 9:15 a.m. Save a student or two who were arriving late, and school principal Melanie Riden, the front entranceway and hall were relatively empty.
According to Dr. Jubal Yennie, Sullivan County director of schools, entrances are locked at that time, and it's unclear how Cowan made entry. Sheriff Anderson said Cowan was "irate," and immediately pointed a .380-caliber, semi-automatic handgun at Riden's head.
It allegedly held one round in the chamber and seven in the magazine.
A receptionist in the school's adjacent office observed the confrontation, according to officials, and immediately alerted students and staff of a lockdown. Anderson says school resource officer Carolyn Gudger then entered the lobby area and drew her gun.
Gudger then pushed Principal Riden behind her and towards the nearby cafeteria, allowing her to escape to safety.
"There's no doubt that Carolyn Gudger probably saved her life at that point," Anderson said.
An intense standoff ensued, with officer and gunman attempting to convince the other to drop their weapon. At one point Cowan allegedly, "tried to take, " Gudger's weapon, according to Anderson, but she would not relinquish it.
"This is not TV," he said, "We don't lay our weapons down if someone asks us to do that."
Police say Gudger continued speaking with Cowan, slowly inching her away from the front foyer, cafeteria and office. She then entered an unoccupied science pod area, with Cowan following.
Authorities say that throughout the ordeal, Cowan didn't ask for anyone in specific. His only alleged question was where is a fire alarm located, but Anderson declined to speculate on why he asked.
"(Gudger) tried everything in the world to negotiate with him, and it wasn't going to happen — it wasn't going to happen," Anderson said. "So I think at that particular time she lured him as she talked, back to this particular area. She got him in a halfway safe zone."
According to police, two minutes had now passed since the initial call to 911. Patrolman Sam Matney and Leut. Steve Williams entered the school from different areas — converging on the science pod to join Gudger and Cowan's standoff.
When ordered to drop his weapon, Cowan allegedly pointed his gun towards the new officers on scene. He then pointed it back at Gudger, according to Anderson, prompting the three officers to fire.
Anderson says he doesn't know how many shots were fired. Since three SCSO officers were involved in the shooting, the Tennessee Bureau of Investigation will be handling the case.
The school's surveillance cameras recorded portions of the incident, according to Anderson. That footage has been handed over the TBI, and will not be released to the public by the Sheriff's Office.
Cowan's body allegedly collapsed near the entrance to the school's library. Though several people were in the library on lockdown, authorities say no students or staff witnessed the actual shooting.
Along with the weapon Cowan was wielding, police discovered a .25-caliber gun in his back pocket. Anderson said it contained five rounds.
"There's so much more to be done on this," Anderson said. "It's not cut and dry. There's a lot more we want to find out, and that the TBI wants to find out."
An investigation into the incident is continuing.
A decade ago, Cowan was arrested after going into the Kingsport Police Department with a loaded .380-caliber tucked into his waistband.
According to court records, Officer David Quillin, now a deputy chief, reported that Cowan entered and asked to speak with him and another officer. It was allegedly about, "a problem that has been discussed with him several times in the past."
Quillin states that as they talked, Cowan informed him that he had a loaded handgun in his possession, and no concealed weapons permit. A subsequent pat-down discovered the weapon.
Cowan ultimately pleaded guilty to going armed and received a sentence of 11 months and 29 days, with all but two days suspended in favor of probation. The judge ordered Cowan to undergo a mental health evaluation and complete any recommended treatment.
Staff writer Kacie Dingus Breeding contributed to this report.