SUTHERLAND SPRINGS, Texas (AP) - The gunman who killed 26 people at a small-town Texas church sent threatening text messages to his mother-in-law before the attack, which appeared to have been driven by domestic tensions, authorities said Monday.

A day after the deadliest mass shooting in state history, investigators also revealed that the shooter had been confronted about domestic violence at least twice in the last five years, including an assault on his ex-wife and a child that ended his Air Force career and another report of violence against a girlfriend who became his second wife.

In the tiny community of Sutherland Springs, population 400, grieving townspeople were reeling from their losses. The dead ranged from 18 months to 77 years old and included multiple members of some families.

"Our church was not comprised of members or parishioners. We were a very close family," said Sherri Pomeroy, the wife of the church pastor, who was out of town with her husband when the attack happened. "Now most of our church family is gone."

The couple's 14-year-old daughter, Annabelle Pomeroy, was among those killed.

The massacre appeared to stem from a domestic situation and was not racially or religiously motivated, Texas Department of Public Safety Regional Director Freeman Martin said.

Based on evidence at the scene, investigators believe Devin Patrick Kelley died of a self-inflicted gunshot wound after he was chased by bystanders, one of whom was armed, and crashed his car.

The 26-year-old shooter also used his cellphone to tell his father he had been shot and did not think he would survive, authorities said.

The investigation showed that Kelley had displayed a pattern of violence spanning years.

In 2014, sheriff's deputies went to his home to check out a domestic violence complaint involving him and his then-girlfriend. People in the house said there was no problem, and no arrests were made. Kelley married the girlfriend two months later.

That same year, Kelley was discharged from the Air Force for the assaulting involving his previous wife. He had served 12 months of confinement after a 2012 court-martial.

He was also charged with misdemeanor animal cruelty in 2014 in Colorado and was the focus of a protective order issued in that state in 2015.

The gunman's family relationships at the First Baptist Church in Sutherland Springs were uncertain. The sheriff said the shooter's former in-laws sometimes attended services at the church but were not there on Sunday. Martin said the text messages were sent to the gunman's mother-in-law, who attended the church. It was unclear if they were referring to the same people.

Once the shooting started, there was probably "no way" for congregants to escape, Wilson County Sheriff Joe D. Tackitt Jr. said.

The gunman, dressed in black tactical gear, fired an assault rifle as he walked down the center aisle during worship services. He turned around and continued shooting on his way out of the building, Tackitt said.

About 20 other people were wounded. Ten of them were still hospitalized Monday in critical condition.

Authorities said Kelley lived in New Braunfels, about 35 miles north of the church. Investigators were reviewing social media posts he made in the days before the attack, including one that appeared to show an AR-15 semi-automatic weapon.

Less than two months ago, Kelley had started a job as an unarmed security guard at a nearby resort.

He "seemed like a nice guy" and did not cause any problems, said Claudia Varjabedian, manager at the Summit Vacation Resort in New Braunfels.

In the Air Force, Kelley served in Logistics Readiness at Holloman Air Force Base in New Mexico from 2010 until his 2014 discharge, Air Force spokeswoman Ann Stefanek said.

On Sunday, the attacker pulled into a gas station across from the church, about 30 miles (48.28 kilometers) southeast of San Antonio. He crossed the street and started firing the rifle at the church, then continued firing after entering the white wood-frame building, Martin said.

As he left, the shooter was confronted by an armed resident who had grabbed his own rifle and exchanged fire with Kelley.

The armed man who confronted Kelley had help from another local resident, Johnnie Langendorff, who said he was driving past the church as the shooting happened. The armed man asked to get in Langendorff's truck, and the pair followed as the gunman drove away.

"He jumped in my truck and said, 'He just shot up the church. We need to go get him.' And I said 'Let's go,'" Langendorff said.

The pursuit reached speeds up to 90 mph. The gunman eventually lost control of his vehicle and crashed. The armed man walked up to the vehicle with his gun drawn, and the attacker did not move. Police arrived about five minutes later, Langendorff said.

The assailant was dead in his vehicle.

"There was no thinking about it. There was just doing. That was the key to all this. Act now. Ask questions later," he said.

Church member Nick Uhlig, 34, who was not at Sunday's service, told the AP that his cousin, who was eight months' pregnant, and her in-laws were among those killed. He later told the Houston Chronicle that three of his cousin's children also were slain.

Officials initially said the dead ranged in age from 5 to 73 years old.

Three weapons were recovered. A Ruger AR-556 rifle was found at the church, and two handguns were recovered from the gunman's vehicle, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives.

The assailant did not have a license to carry a concealed handgun, Martin said.

The church has posted videos of its Sunday services on a YouTube channel, and authorities said they were reviewing video footage recorded inside the church.

In a video of its Oct. 8 service, a congregant 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.

Sunday's attack came on the eighth anniversary of a shooting at Fort Hood, between Austin and Waco, where 13 people were killed and 31 others wounded by a former Army major.

The previous 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.

One of the most infamous mass shootings in American history happened when Marine sniper Charles Whitman climbed a clock tower at the University of Texas' Austin campus in 1966 and began firing on people below. He killed 13 and wounded nearly three dozen others after killing his wife and mother before heading to the tower. One victim died a week later, and medical examiners attributed a 17th death to Whitman in 2001.