Alleged Texas gunman identified as former military man discharged following domestic assault

The gunman responsible for the mass shooting at a small Texas church has been identified as 26-year-old Devin Patrick Kelley, a former military member with a history of domestic violence.

Two officials - one a US official and the other in law enforcement - spoke to The Associated Press on the condition of anonymity.

He opened fire on the congregation inside the First Baptist Church in Sutherland Springs during Sunday morning service, killing at least 26 people and wounding 20 others.

Devin Patrick Kelley has been identified as a suspect in the shooting. Source: Facebook

The US official says Kelly lived in a suburb of San Antonio and he doesn't appear to be linked to organised terrorist groups.

The official says investigators are looking at social media posts Kelley may have made in the days before the attack, including one that appeared to show an AR-15 semiautomatic weapon.

After the shooting, Kelley was reportedly shot by an unidentified "neighbour", prompting Kelley to drop his rifle and flee in his vehicle.

Soon afterward, the suspect crashed his vehicle near the border of neighbouring Guadalupe County and was found dead inside with a cache of weapons.

It was not immediately clear if the suspect killed himself or was hit when the citizen fired at him outside the church, authorities said.

Just days earlier, Kelley posted a photo of an assault rifle with the caption "she's a bad b****".

Just days before the massacre, Kelley shared this ominous photo on his Facebook page. Source: Facebook

Kelley's Facebook page was taken down in the immediate aftermath of the shooting, however screenshots showed images of two small children as well as the semiautomatic rifle.

According to the Daily Beast, Kelley joined the US Air Force after completing high school in 2009.

He was discharged from the service in 2014 with defence department documents stating Kelley was court-martialed in 2012 for assaulting his wife and their child.

Following the assault charge, Kelley was sentenced to 12 months confinement and was twice reduced in rank to basic airman, the Daily Beast reports.

The victims of his shooting rampage ranged in age from five to 72 years old, law enforcement officials told a news conference.

Among the dead was the 14-year-old daughter of Pastor Frank Pomeroy, Annabelle.

Anabelle Pomeroy has been identified as one the victims in the Texas church shooting. Source: Facebook

Law enforcement officials stand within a cordoned off area at the church. Source: AAP

"We don't think he had any connection to this church," Wilson County Sheriff Joe Tackitt told CNN.

"We have no motive."

A US official says Kelley lived in a suburb of San Antonio and he doesn't appear to be linked to organised terrorist groups.

The official investigators added that they were looking at the social media posts Kelley may have made in the days before the attack

Officers man a barricade near the First Baptist Church of Sutherland Springs after the fatal shooting. Source: AAP

"We are dealing with the largest mass shooting in our state’s history," Texas Governor Greg Abbott said at the news conference.

"The tragedy of course is worsened by the fact that it occurred in a church, a place of worship where these people were innocently gunned down."