SUTHERLAND SPRINGS, Texas (USA TODAY) — About half of the 26 people killed in a gunman's assault on a church in this quiet, rural town outside San Antonio were children, Wilson County Sheriff Joe Tackitt said Monday.

Tackitt said all the bodies had been removed from the First Baptist Church, and all but one of the victims had been identified by investigators.

“It’s just a horrific sight,” Tackitt said. “You don’t expect to walk into a church and see something like that, especially when all the bodies were there, and seeing the children. That’s what hurts the most.”

The Texas Department of Safety on Monday identified the shooter as Devin Kelley, 26, of New Braunfels. Tackitt said Kelley's in-laws had previously attended services at the church but were not there during the deadly rampage on Sunday.

Kelley was court-martialed in 2012 for assaulting his spouse and their child, receiving a bad conduct discharge from the Air Force and 12 months of confinement.

"We know that his ex-in-law, or in-laws, came to church here from time to time," Tackitt told CNN. "They were not here yesterday."

When asked whether he expects the death toll to rise, the sheriff said he believes most of those hospitalized are in stable condition. He said there are about 20 people still in the hospital.

The church normally posted video of its services online, Tackitt said. But he said there was "very little" video from Sunday's service.

The killer was pursued by a local resident armed with a gun. As law enforcement responded, the suspect drove off a roadway at the Wilson County/Guadalupe County line, state DPS official Freeman Martin said.

The shooter was found "deceased in his vehicle,” he said, but officials were not immediately certain whether the fatal wound came from a self-inflicted gunshot or from the person pursuing him.

Authorities did not immediately identify a motive for the attack. The sheriff said he has spoken with the neighbor who is being credited with chasing the gunman down.

“He doesn’t believe he’s a hero, but I believe he is,” Tackitt said, adding that the man doesn’t want to speak to any media.

“If he hadn’t been there, the guy could have possibly gotten away, you know because, I mean no one would have seen what type of vehicle he was driving,” he said. “There’s another church two miles down the road over there. He could have stopped in there too.”

Speaking to reporters late Sunday, Texas Gov. Greg Abbott said, "There are no words to describe the pure evil that we witnessed in Sutherland Springs today."

Abbott said officials were cautiously releasing information on the shooting, including the names of victims, who ranged in age from 5 to 72 years old.

Officials said 23 of the 26 victims were shot inside the church.

“There’s a lot of information," Abbott said. "We want to piece the puzzle together.”

Tackitt said he knew quite a few of the people who were in the church, later describing the community as one where “pretty much everyone knows everyone.” He said recently the church hosted a fall festival.

“A week later this happens,” he said.

He confirmed a family had been killed, though he didn’t confirm number of people in the family, describing it as a “a pretty high number.” Tackitt said he’s known the family “forever.”

Frank Pomeroy, who is pastor at the church, told ABC News he was out of town when the rampage took place, but that his daughter was killed. Annabelle, 14, "was one very beautiful, special child,” Pomeroy said.

Tackitt confirmed that a visiting pastor Sunday was one of the victims.