TOWNVILLE, S.C. -- When two volunteer firefighters rolled up to an elementary school shooting, they said they found only a wrecked black pickup truck at the playground. There was no gunman, and no one inside the truck.

Within minutes, though, they performed actions that led to them being hailed as heroes throughout their tight-knit South Carolina hometown: One went inside to help treat the wounded and the other searched for the shooter.

"This was more than just another call to us. This incident occurred in the school where our children and the children of the community attend," Townville Fire Chief Billy McAdams said Thursday during a news conference, pausing to collect himself as he recalled the harrowing events of the day before.

Authorities say the teen shot his father at their home before driving the pickup 3 miles down a country road lined with chicken houses and pine trees to Townville Elementary School. He only had to make two turns to arrive at the red brick school, where he crashed the truck, got out and fired at a door as it was being opened for recess, authorities said.

Bullets struck two students and a first-grade teacher, and the building was immediately placed on lock down.

Anderson 4 Superintendent Joanne Avery said staff saved lives by flawlessly implementing active-shooter training drills conducted with students over the past few years -- at Townville Elementary, most recently just last week. All six schools in the rural district went through annual drills in August, but a nearby carjacking prompted Townville officials to do it again, she said.

All district administrators trained just Monday on a new crisis response app put on their cellphones, which included an active-shooter scenario.

Though shot in the shoulder, the teacher "was with-it enough" to close the door, lock it and barricade the students, Avery said.

"If he'd gotten in the school, it would've been a different scenario," she said.

The shooter then fired toward students on the playground but missed. A teacher who heard the first gunshot was able to get those students safely inside, Avery said.

The school's staff "put their fear to the side because they put those children first," she said.

One of the wounded, 6-year-old Jacob Hall, remained in critical condition Thursday and was said to be fighting for his life. A sign outside a diner conveyed the sentiments of an entire community: "Pray for Jacob. Pray for Townville."

The teacher who was shot in the shoulder and another student who was hit in the foot were treated and released from a hospital, officials said. The teen was arrested minutes after the shooting and a Family Court hearing was set for Friday to determine if he should remain in jail or be released.

Classes are scheduled to resume at the school Monday, but second-grader Mattie LeCroy doesn't want to go. Asked whether she was scared to return to school, the blond-haired 7-year-old simply nodded her head "yes" after dropping off flowers for Jacob with her mom at the town's fire station.

The violence was a punch in the gut to people around Townville, where residents say some families have lived on the same land since before the Civil War. Outside a church where workers offered counselling and other aid to residents, both U.S. and Confederate flags decorate graves in the burial yard.

"It's just a shock. Why in the world would that boy do that?" said Douglas Ayers, who lives on the road linking the Osborne home and the school.

Authorities said they don't yet know a motive for the shooting and they were not sure if the students and teacher were targeted or shot randomly.

Anderson County Sheriff John Skipper said the teen had been homeschooled, but the reason isn't clear. Avery said the teen attended Townville Elementary through fifth grade then transferred to a school in neighbouring Oconee County.

The fire chief said he and firefighter Jamie Brock were working on his farm when they got the call about an active shooter at Townville Elementary. They rushed to the school and found the empty pickup.

Teachers told them there were wounded inside, and Brock suggested to the fire chief that he go inside to help because he was a paramedic. Alongside a school nurse, the chief attended to Jacob, who was the most seriously injured.

In the meantime, law enforcement swarmed the school and Brock looked for the shooter, finding him near the back of the school building.

"Feeling it was imperative to the safety of the students, the teachers and all the responders that were on site, he immediately confronted and subdued that shooter," the chief said. "He was able to keep him on the ground until law enforcement could place him into custody."

Authorities have not released the teen's name or specific age.

Anderson County Coroner Greg Shore said the teen, crying and upset, called his grandmother's cellphone at 1:44 p.m. Wednesday. The grandparents couldn't understand what was going on, so they went to his home just a couple hundred yards away. When they got there, they found 47-year-old Jeffrey Osborne dead and their grandson gone.

About one minute later, authorities received a 911 call from a teacher at the school of about 300 pre-kindergarten to sixth-graders.

The teen's mother, Tiffney Osborne, said in a statement that the family "cannot express the devastation we feel at the loss of our beloved Jeff." She was at work at the time of the shooting, the sheriff said.

Both Tiffney and Jeffrey Osborne's first marriages ended in divorce before they got married. They each had children, who are now adults, with their exes.

Authorities said audio from the 911 calls will not be released while the investigation is ongoing.

In a statement read by the fire chief, Brock said he doesn't want attention for his actions.

"The true heroes of yesterday's senseless tragedy are the teachers who put their lives on the line to protect the students and the principal, through fears of her own, did what was right to ensure the safety of those students," he said. "They deserve to be called the heroes, and I tip my hat to them."

Associated Press writers Seanna Adcox, Jack Jones and Meg Kinnard contributed to this report from Columbia, South Carolina.