Motive of Texas mass shooter 'domestic,' not 'racial or religious' as feared

"This was not racially motivated, it wasn't over religious beliefs. There was a domestic situation going on with the family and in-laws," Freeman Martin, regional director of the Texas Department of Public Safety, told a news conference.

"The suspect's mother-in-law attended this church," he said.

The 26-year-old shooter Devin Patrick Kelley had sent "threatening texts" prior to the mass shooting.

Sunday's carnage, which came just five weeks after the worst gun massacre in modern US history.

It saw the gunman wearing a bulletproof vest use an assault rifle to open fire on the congregation of a small-town Texas church, killing 26 people and wounding 20 more.

US President Donald Trump said his country was living in "dark times", but with calls for stricter gun control reinvigorated. He insisted the latest tragedy "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 US.

Law enforcement later found Kelley dead in his car, which had crashed on the Wilson-Guadalupe county line.

Multiple weapons were found in the car, which was processed by bomb technicians.

"There's so many families who have lost family members. Fathers, mothers, sons, and daughters," Governor Greg Abbott said, warning the toll could rise.

"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. We mourn their loss, but we support their family members."

Agencies contributed to this report.