A lone gunman stormed a Texas church on Sunday, opening fire on the congregation and killing at least 26 people leaving many more injured.

The incident at First Baptist church in Sutherland Springs, a small town 30 miles south-east of San Antonio, is one of the worst gun rampages in recent US history and resulted in the highest death toll ever from a mass shooting in Texas.

The dead range from aged five to 72, according to the officials, with 23 dying inside the church, two outside it and one after being taken to hospital.

The lone suspect, dressed in black tactical gear and a ballistic vest, drove up to the church building around 11.30 am local time and opened fire using an assault rifle.

The killer was reported as former Air Force serviceman Devin Patrick Kelley, who left after a court martial in 2014 where he received a bad conduct discharge for assaulting his wife and child. Police have not confirmed Kelley as a suspect but officers were seen outside his house about 35 miles from Sutherland Springs.

'We are dealing with the largest mass shooting in our state's history,' Texas Governor Greg Abbott said at a 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.'

He added: 'There are so many families who have lost family members, and it occurred in a church, in a place of worship. That's where these people were mown down. We mourn their loss.'

The pastor of First Baptist, Frank Pomeroy, and his wife Sherri, were away at the time of shooting but their 14-year-old daughter was among the dead.

Pastor Frank Buford, of neighbouring River Oaks church, said a makeshift community centre was acting as a meeting point for relatives and friends of the victims.

'We're holding up as well as we can – we are a strong community, we are strong in our faith,' he told local reporters, describing Sutherland Spring's tiny community with only a few hundred residents.

'We have a post office, two churches and a dollar store,' he said. 

The town gathered for a prayer vigil on Sunday night after the incident.

After leaving the church, the gunman was fired on by a local resident with a rifle. The suspect dropped his Ruger assault weapon and fled in his vehicle, said Freeman Martin, regional director of the Texas Department of Public Safety.

Soon afterward, the suspect crashed the vehicle near the border of a neighbouring county and was found dead inside with a cache of weapons. It was not immediately clear if he killed himself or was hit when the resident fired at him outside the church, authorities said.

The shooting comes after 58 people died and 546 were injured in another mass shooting in Las Vegas last month. Following that incident Donald Trump was reluctant to engage in a debate about gun laws and so far has limited his response to sending his prayers.

Speaking from Tokyo he blamed the incident on the attacker's 'mental health problems' and said it 'isn't a guns situation.' He said it was lucky there was an armed local on the scene who shot at the attacker, otherwise 'it would have been much worse'.

He ordered flags on all federal buildings to be flown at half staff and said: 'This act of evil occurred as the victims and their families were in their place of sacred worship.

'Through the tears and through the sadness we stand strong, oh so strong.'

Additional reporting by Reuters.