The Air Force never submitted Devin Patrick Kelley's criminal history to the FBI, Trump administration officials tell the Associated Press.

Kelley is accused of walking into the First Baptist Church in Sutherland Springs, Texas, in black tactical gear with a military-style rifle and killed 26 people and injured 20 others. 

• Motive of shooter still unknown
• Law enforcement: Devin Kelley is name of shooter
• Mother-in-law says she received threatening text from Kelley
• Officials: Kelley does not appear link to organized terror group
• Texas Department of Safety: Armed resident grabbed firearm from gunman
• Texas no stranger to mass shootings
• RELATED: Texas church shooting leaves 26 dead

Officials say Kelley was able to buy several guns over the years, even though he was denied a concealed weapons license in Texas.

Kelley received a bad-conduct discharge from the Air Force for allegedly assaulting his spouse and child, and was sentenced to 12 months’ confinement after a 2012 court-martial. Kelley served in Logistics Readiness at Holloman Air Force Base in New Mexico from 2010 until his discharge, Air Force spokeswoman Ann Stefanek said.

Because of that, he should not have been able to buy firearms. Pentagon rules require that information be sent to the FBI.

This is a developing story. Check back for the latest.

Freeman Martin, regional direct of the Texas Department of Public Safety, said investigators at the scene said he may have died of a self-inflicted gunshot wound, but stated that an autopsy will be performed.

There was debate over how Kelley, a former United States Air Force member, died. There was speculation that he either died in an auto accident while being chased by two residents or that one of the residents had shot him after the crash or that he killed himself. 

The armed man who confronted Kelley had help from another local resident, Johnnie Langendorff, who told KSAT TV that he was driving past the church as the shooting happened. He did not identify the armed resident but said the man exchanged gunfire with the gunman, then asked to get in Langendorff’s truck and the pair pursued as the gunman drove away.

"I never got a look at him. I never really saw him. I just saw the gunfire," he described.

Langendorff says the gunman eventually lost control of his vehicle and crashed. He says the other man walked up to the vehicle with his gun drawn and the suspect did not move. He stayed there for at least five minutes, until police arrived.

“I was strictly just acting on what’s the right thing to do,” Langendorff said. 

Martin also stated that Kelley did not have a licence to carry, but confirmed that all the firearms that officials found were purchased by him.  

In an impromptu press conference Monday morning, Wilson County Sheriff Joe Tackitt said the death toll remains at 26 with 20 people injured. The victims have not been identified but at least eight of them were believed to be from the same family and one was the pastor’s daughter. Victims' ages ranged 18 months old to 72 years old. Tackitt believes 12 to 14 children were affected, either dead or injured.

FBI Christopher Combs said that Kelley’s mother-in-law attended the church and she had received a threatening text from Kelley.

First Baptist Church remains an active crime scene and the sheriff said that is how it will be for a while. All bodies have been removed from the church and sent to Bexar County, but investigators will continue looking around the area for more clues on what went down.

A U.S. official said Kelley lived in a San Antonio suburb and did not appear to be linked to organized terrorist groups. Investigators were looking at social media posts Kelley made in the days before Sunday’s attack, including one that appeared to show an AR-15 semiautomatic weapon.

The Pentagon confirmed that deceased shooting suspect Devin Kelley was a member of the United States Air Force but details of his service were not immediately disclosed.

At the news conference, the attacker was described only as a white man in his 20s who was wearing black tactical gear and a ballistic vest when he pulled into a gas station across from the First Baptist Church in Sutherland Springs, about 30 miles southeast of San Antonio, around 11:20 a.m.

The gunman crossed the street and started firing a Ruger AR rifle at the church, said Freeman Martin, a regional director of the Texas Department of Safety, then continued firing after entering the white wood-frame building, where an 11 a.m. service was scheduled.

Wilson County Sheriff Joe D. Tackitt Jr., whose territory includes Sutherland Springs, said there was likely “no way” for the church congregation to escape once the shooting started.

“You’ve got your pews on either side. He just walked down the center aisle, turned around and my understanding was shooting on his way back out,” said Tackitt, who said the shooter also carried a handgun but that he didn’t know if it was fired.

Tackitt described the scene inside the church as “terrible.”

“It’s unbelievable to see children, men and women, laying there. Defenseless people,” Tackitt said. “I guess it was seeing the children that were killed. It’s one thing to see an adult, but to see a 5-year-old ...”

As he left, the shooter was confronted by an armed resident who “grabbed his rifle and engaged that suspect,” Martin said. A short time later, the suspect was found dead in his vehicle at the county line.

Gov. Greg Abbott called the attack the worst mass shooting in Texas history.

“There are no words to describe the pure evil that we witnessed,” Abbott said. “Our hearts are heavy at the anguish in this small town, but in time of tragedy, we see the very best of Texas. May God comfort those who’ve lost a loved one, and may God heal the hurt in our communities.”

All bodies have been removed from the church and sent to Bexar County, but investigators will continue looking around the area for more clues on what went down. 

Among those killed was the church pastor’s 14-year-old daughter, Annabelle Pomeroy. Pastor Frank Pomeroy, and his wife, Sherri, were both out of town when the attack occurred, Sherri Pomeroy wrote in a text message.

“We lost our 14-year-old daughter today and many friends,” she wrote. “Neither of us has made it back into town yet to personally see the devastation. I am at the charlotte airport trying to get home as soon as i can.”

Federal agents swarmed the small rural community of a few hundred residents, including ATF investigators and the FBI’s evidence collection team.

Gloria Rodriguez Ximenez know one of the shooting victims in the sparsely populated county.

"So much hurt for a small town, for a small community. So united. Never in a million years would I expect anything like this. I could never imagine anything like this happening here," she said.

Church member Nick Uhlig, 34, was not at Sunday’s service, said his cousin, who was 8 months pregnant, and her in-laws were among those killed.

“We just gathered to bury their grandfather on Thursday,” he said, shaking his head.

President Donald Trump, who was in Japan, called the shooting an “act of evil” and said he was monitoring the situation.

The governor expressed appreciation for many local and state leaders, as well as Trump, who called from overseas. Officials said no identities of any victims are being released at this time, as authorities are working to notify family members.

Later Sunday, two sheriff’s vans were parked outside the gate of a cattle fence surrounding the address listed for Kelley on the rural, western outskirts of New Braunfels, north of San Antonio.

Ryan Albers, 16, who lives across the road, said he heard intensifying gunfire coming from that direction in recent days.

“It was definitely not just a shotgun or someone hunting,” Albers said. “It was someone using automatic weapon fire.”

The church has posted videos of its Sunday services on a YouTube channel, raising the possibility that the shooting was captured on video.

In a video of its Oct. 8 service, a congregant who spoke and read Scripture pointed to the Oct. 1 Las Vegas shooting a week earlier as evidence of the “wicked nature” of man. That shooting left 58 dead and more than 500 injured.

Until Sunday, the deadliest mass shooting in Texas had been a 1991 attack in Killeen, when a mentally disturbed man crashed his pickup truck through a restaurant window at lunchtime and started shooting people, killing 23 and injuring more than 20 others.

The University of Texas was the site of one of the most infamous mass shootings in modern American history, when U.S. Marine sniper Charles Whitman climbed the Austin campus’ clock tower in 1966 and began firing on stunned people below, killing 13 and wounding nearly three dozen others. He had killed his wife and mother before heading to the tower, one victim died a week later and medical examiners eventually attributed a 17th death to Whitman in 2001.

Associated Press contributed to this story.