SUTHERLAND SPRINGS, United States (AFP) — Investigators said Monday they suspect a “domestic situation” was behind the rampage by a US Air Force veteran who killed 26 people with an assault rifle in a small-town Texas church, in the latest mass shooting to stun the United States.

Ten people remained in critical condition a day after Devin Patrick Kelley, a 26-year-old private security guard, burst into the rural Baptist church during Sunday morning services and sprayed bullets at the congregation, wounding another 20.

Governor Greg Abbott said meanwhile that Kelley, who was armed with an AR-15 rifle and two handguns, had been denied a gun permit in the state of Texas and should not have legally had access to weapons.

President Donald Trump, who is travelling in Asia, said the United States was living in “dark times” but brushed off calls for stricter gun control, saying the latest tragedy, which left eight members of one family dead, “isn’t a guns situation.”

The authorities said Kelley apparently died of a self-inflicted gunshot wound in his car after opening fire Sunday morning on worshippers in the First Baptist Church in Sutherland Springs, a rural community of rolling hills and ranches of nearly 400 people near San Antonio.

Kelley, who received a bad conduct discharge from the Air Force, was dressed in black and was wearing a bulletproof vest and a black mask with a skull face when he attacked the church, officials said.

Two men were being lauded as heroes for chasing Kelley’s vehicle after he sprayed the church with gunfire.

One of the men raced out of his home across the street with his own AR-15 rifle and wounded Kelley as he emerged from the church and headed for his car in the parking lot, officials said. Freeman Martin of the Texas Department of Public Safety said the dead included an 18-month-old toddler and the oldest victim was 77.

He said 10 people remained in critical condition, four were in serious condition and six were in stable condition or had been released from hospital.

According to reports, eight members of the Holcombe family were among the dead, who also included the pastor’s 14-year-old daughter.

Sunday’s carnage came just five weeks after the worst gun massacre in modern US history, the murder of 58 people by a heavily armed retired accountant who opened fire on a country music concert in Las Vegas.

Martin said the investigation was focusing on reports that Kelly had sent threatening texts to his mother-in-law, who attended the church but was apparently not there on Sunday morning. “There was a domestic situation going on with the family and in-laws,” he said. “We know that he expressed anger towards his mother-in-law.”

Governor Abbott said the shooting was not a “random act.”

“Obviously the motive was completely deranged,” he told CBS This Morning. “This is a man who had some mental health issues apparently long before this.”

According to the Air Force, Kelley served at a base in New Mexico starting in 2010 before being court-martialled in 2012 on charges of assaulting his wife and a child.

He was sentenced to 12 months in confinement and received a “bad conduct” discharge in 2014, Air Force spokeswoman Ann Stefanek said.

Officials said Kelley was armed with a Ruger AR-15 rifle and had two handguns in his vehicle, a Glock 9mm and a Ruger .22 but Abbott said Kelley should not have been allowed to have a gun. “He tried to get a gun permit in the State of Texas and was denied that permit,” Abbott said. “Under the current system of federal law he should have been prevented to make this purchase.” Kelley was from the town of New Braunfels, 30 miles (50 kilometres) from Sutherland Springs, and his in-laws attended the church, Wilson County Sheriff Joe Tackitt said.

“They were not here yesterday,” he said. “So we don’t know why he actually showed up.”

Tackitt said a man living nearby engaged Kelley in a “firefight” as he was leaving the church. The resident then stopped a man in a truck, Johnnie Langendorff, and together they pursued Kelley for about 10 to 12 minutes at speeds which Langendorff said reached up to 95 miles per hour (150 kilometres per hour).

“I had to catch the guy. I had to make sure he was caught,” Langendorff told CNN.

“There was some gunfire exchanged, I think, on the roadway also and then (Kelley) wrecked out,” Tackitt said. “At this time we believe that he had a self-inflicted gunshot wound.”

Martin said Kelley called his father from the car before he crashed and said he was wounded and didn’t think he would make it.

Speaking in Tokyo as part of his Asia tour, President Trump dubbed the gunman as “deranged” and said the most recent mass shooting to hit the United States “isn’t a guns situation.”

“I think that mental health is your problem here,” Trump told journalists when asked if gun control could reduce the rampant firearms violence plaguing the country.

Late Sunday, mourners held a candlelight vigil for victims in the tiny town. “We lost a lot of good friends,” said Robert Kunz, 50, owner of Sutherland Springs Tire & Battery.

“I feel like the guy got what he deserved,” he said. “You’re going to hate me for this, but I think they need to let the buzzards pick at him.”