Video report by ITV News Washington Correspondent Robert Moore
A gunmen who killed 26 people at a church in Texas' worst ever mass shooting may have been motivated by a domestic dispute with his in-laws, authorities have suggested.
Devin Patrick Kelley, 26, opened fire on the congregation at First Baptist Church in Sutherland Springs, leaving more than two dozen dead and 20 others injured.
The ages of the victims ranged from five to 72. The wife of the church pastor said the couple's 14-year-old daughter was among those killed.
Authorities said ten of the wounded were in a critical condition, and warned the death toll may rise further.
Texas police indicated they were looking at a "domestic situation" between Kelley and his mother-in-law, who was a member of the church.
Kelley had previously sent "threatening texts" to his in-law, a press conference heard.
"Everybody wants to know is why did this happen? It's a senseless crime, but I can tell you that there was a domestic situation going on within this family," said Freeman Martin, regional director with Texas Department of public safety.
"The suspect's mother-in-law attended this church. We know that she had received threatening texts from him."
Wilson County Sheriff Joe D. Tackitt Jr had previously told CNN that the gunman's former in-laws attended services at the church "from time to time" but were not in attendance on Sunday.
Kelley fled the scene in his car, and was found dead inside the vehicle after a short chase by a bystander who had been passing in his car.
Police today revealed he had three guns with him during the attack - a rifle found at the church and two handguns in his car.
As police scramble to look into Kelley's background, it emerged that the attacker had managed to obtain firearms despite reportedly being barred from owning a gun under Texan laws.
President Donald Trump condemned the shooting as an "act of evil" but insisted that it did not show the need for more firearms controls.
"This isn't a guns situation," he said in comments made from Japan.
"I think mental health is your problem here. This was - based on preliminary reports - a very deranged individual. A lot of problems, over a long time."
It has emerged that Kelley had been dishonorably discharged from the Air Force several years ago for allegedly assaulting his spouse and a child.
That meant he would not normally be allowed to own a gun - and the Texas resident had reportedly previously applied for and been denied a gun licence by the state's authorities.
"By all the facts that we seem to know, he was not supposed to have access to a gun,” Texas Governor Greg Abbott told CNN. “So how did this happen?”
Kelley's relatives said they were stunned to learn that he had carried out a shooting.
His uncle told NBC News: "I never in a million years could of believed Devin could be capable of this kind of thing. I am numb."
The first person to be named among the victims of the shooting was 14-year-old Annabelle Pomeroy, the daughter of church pastor Frank and his wife Sherri.
"We lost our 14-year-old daughter today and many friends," wrote Mrs Pomeroy in a message, which said the couple had been out of town.
"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."
Church member Nick Uhlig, 34, who was not at Sunday's service, said his cousin, who was eight months pregnant, and her in-laws were among those killed.
He later told the Houston Chronicle three of his cousin's children also were killed.
Texas authorities said that of the 20 wounded, ten are fighting for life in a critical condition.
Four remain in a serious condition, and the six were in stable condition or had been released from hospital.
One hospital in Floresville, Texas, about 10 miles from the shooting, said they were treating "multiple" victims with gunshot wounds.
Donald Trump has paid tribute to the victims in a statement.
Texas Governor Greg Abbott called the shooting an "evil act," while Senator Ted Cruz, also from Texas, offered prayers to the victims.