(CNN) A minute before a teen allegedly opened fire at an elementary school playground in South Carolina, he called his grandparents' cell phone, sobbing and mumbling unintelligibly, authorities say.

It was 1:44 p.m. local time.

His grandparents could barely hear the 14-year-old because of his crying , CNN affiliate WYFF-TV in Greenville reported. So they headed next door, where he lived, to check on him.

But instead the grandparents found their son -- the teen's father -- dead in the home.

At about 1:45 p.m. Wednesday, a teacher called 911 to report a shooting at the playground behind nearby Townville Elementary School

The school is southwest of Greenville -- near the Georgia line.

What happened?

Police say the shooting started in a parking lot by the Townville Elementary School playground.

The teen allegedly drove a Dodge Ram onto school property and jumped a fence to access the playground, according to CNN affiliate WHNS-TV in Greenville. It said he never entered the school.

By the time the gunfire stopped, he had wounded two students and a teacher, authorities said.

Deputies detained the teen, who was not identified because he is a minor, after a volunteer firefighter took him down.

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3 wounded, father dead

The father, who was identified as Jeffrey Osborne, 47, suffered fatal gunshot wounds, Anderson County Coroner Greg Shore said.

At the elementary school two miles away, one male student was critically injured with a gunshot to the leg, and another boy was struck in the foot. A female teacher was wounded in the shoulder, sheriff's Capt. Garland Major said.

The teacher and one student were treated at a local health center and released Wednesday evening, hospital spokesman Ross Norton told CNN. A third victim was transported to a hospital in critical condition, officials said.

First-grader Jacob Hall was put on life support Thursday after suffering brain injury due to blood loss, according to CNN affiliate WHNS

"As long as his heart's beating, we've got hope," his great-aunt Rebecca Hunnicutt told WHNS.

"Jacob was one of these kids who you would swear was carved out of cream cheese," Hunnicutt said. "He is as beautiful on the inside as he is on the out."

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'There was a bunch of kids crying'.

The teen started firing after getting out of his vehicle, Anderson County Sheriff John Skipper said.

It appeared he was headed toward the school, but teachers locked doors to prevent him from getting in, authorities said.

"I don't know how they knew to go in the bathroom, but I know her teacher was shaken up. I know all the kids were scared. There was a bunch of kids crying. She didn't talk for about five minutes when I got her."

It is unclear whether the teen in custody knew any of the school victims. The motive for the shooting is unclear, but terrorism has been ruled out, authorities said. CNN has not determined whether the teen has an attorney.

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Longtime firefighter helped save lives

School nurses and emergency responders saved the life of the boy who was shot in the leg, said Scott Stoller, the director of Emergency Medical Services in Anderson County.

"Training, proper equipment is absolutely critical and without their early intervention the outcome would have been very different," he said.

One of the people credited with saving lives is firefighter Jamie Brock. The 30-year veteran volunteer firefighter, who was not armed, took down the suspect on the playground, WYFF reported. Brock declined to talk to the media.

Active shooter training

The school has no video cameras, according to Joanne Avery, superintendent for Anderson County District 4. She told WYFF that the staff had undergone active-shooter training, which proved useful during the shooting.

"We are heartbroken about this senseless act of violence," Avery said

Townville Elementary canceled classes for the rest of the week and is providing counseling services.

The school has about 280 students and 30 school employees, according to its website.