A gunman dressed all in black, and wearing a tactical gear including a bullet-proof vest, walked into a church in a small Texas church on Sunday and opened fire as the congregation were involved in weekly service - leaving at least 26 dead and about 20 others injured.

The mass shooting occurred at the First Baptist Church in Sutherland Springs, about 30 miles from San Antonio, with President Donald Trump denouncing it as an "act of evil". The victims ranged in age from five to 72, according to police.

One of those killed was 14-year-old Annabelle, the daughter of the church's Pastor Frank Pomeroy. Pastor Pomeroy and his wife Sherri were not in town as the gunman stuck, arriving at a petrol station across the street from the church at around 11.20am local time.

The weekly service started at 11am, with the congregation waiting to hear a sermon around the time the shooter arrived. The man, who police have not yet confirmed the identity of, has been named in US media as Devin Patrick Kelley, 26.

Police said the gunman crossed the street in his vehicle, got out and began firing using a Ruger AR assault-type rifle. He then moved to the right side of the church, continuing to fire and then into the building - still shooting bullets.

As he left, he was confronted by a resident who grabbed his rifle and then began to fire at him as he fled. The neighbour of the church then chased the shooter who left the scene in his vehicle before leaving the road at the border with Guadalupe County. He was found dead inside the vehicle, although authorities are not sure if the shooter died from a self-inflicted wound, or whether it was from the resident.

Texas church shooting Show all 9 1 /9 Texas church shooting Texas church shooting The site of the mass shooting at First Baptist Church in Sutherland Springs, Texas Reuters Texas church shooting First responders are at the scene of shooting at the First Baptist Church Reuters Texas church shooting Enrique and Gabby Garcia watch investigators at the scene of the mass shooting AP Texas church shooting Law enforcement officials investigate the scene at the First Baptist Church in Sutherland Springs, Texas Reuters Texas church shooting Carrie Matula embraces a woman after a fatal shooting at the First Baptist Church in Sutherland Springs Associated Press Texas church shooting Law enforcement officials gather near the First Baptist Church Getty Images Texas church shooting Community members come together for a candlelight vigil for the victims of the deadly church shooting in Sutherland Springs Laura Skelding/AP Texas church shooting Mourners participate in the candlelight vigil held for the victims Jay Janner/Austin American-Statesman via AP Texas church shooting A vehicle is hauled onto a flatbed truck where the suspect in a deadly church shooting was found dead in Guadalupe County William Luther/Austin American-Statesman via AP

The gunman left 23 dead inside the church, two outside, while another died on the way to the hospital. The death toll could increase given the number of injured.

Representative Henry Cuellar of Texas, who said he was briefed by law enforcement authorities, said the gunman came from Comal County, which is northeast of San Antonio.

Speaking at an evening press conference, Texas Governor Greg Abbott said: "We are dealing with the largest mass shooting in our state's history”.

“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.

Later, speaking from Tokyo on a trip to Japan, Mr Trump said: "Our hearts are broken but in dark times — and these are dark times — such as these, Americans do what they do best." He says Americans will pull together to help those suffering. He said he would lend his administration's full support to Texas.

Video on KSAT television showed first responders taking a stretcher from the church to a waiting AirLife helicopter. Some victims were taken by medical helicopter to the Brooke Army Medical Center.

Megan Posey, a spokeswoman for Connally Memorial Medical Center, which is in Floresville and about 10 miles from the church, said “multiple” victims were being treated for gunshot wounds. She declined to give a specific number but said it was less than a dozen.

A woman who lives about 10 minutes away from Sutherland Springs in Floresville and was monitoring the chaos on a police scanner and in Facebook community groups, said that everyone knows everyone in the sparsely populated county.

“This is horrific for our tiny little tight-knit town,” said Alena Berlanga of the town, which has a population of about 600. “Everybody's going to be affected and everybody knows someone who's affected,” she told Reuters.

Witnesses close to the small church reported hearing a rapid barrage of about 20 gunshots. “It was very close,” Carrie Matula, who had been working in a store across the street from the church, told CNN. “It was semi-automatic, rapid fire. This is just devastating in a small town like this.” There has been no official confirmation yet of the type of weapon used.

Federal law enforcement swarmed the area, including Alcohol, Tobacco and Firearms (ATF) investigators and members of the FBI's evidence collection team.

Friends and family gathered near the church waiting for words of what had happened to loved ones, tears flowed with many incredibly anxious.

“We're shocked. Shocked and dismayed,” said state Senator Judith Zaffirini, a Laredo Democrat whose district includes Sutherland Springs. “It's especially shocking when it's such a small, serine area. These rural areas, they are so beautiful and so loving.” ​

Regina Rodriguez arrived at the church a couple of hours after the shooting and walked up to the police barricade. She hugged a person she was with. She had been at an amusement park with her children when she heard of the shooting.

She told the Associated Press that her father, 51-year-old Richard Rodriguez, attends the church every Sunday, and she hadn't been able to reach him. She said she feared the worst.

Nick Uhlig, 34, is a church member who didn't go Sunday morning because he was out late Saturday night. He said his cousins were at the church and that his family was told at least one of them, a woman with three children and pregnant with another, is among the dead. He said he hadn't heard specific news about the other.

According to a 2015 listing in the national directory of the Southern Baptist Convention, the Sutherland Springs church was formed in 1926 and has nearly 270 members. Services are offered in English and Spanish and draw an average of about 180 people on Sundays.

According to the Gun Violence Archive, which tracks gun violence, there has now been more than 300 mass shootings in the US this year. The deadliest mass shooting in modern US history was just over a month ago in Las Vegas. Fifty-eight people were killed and more than 500 injured by gunman Stephen Paddock.

As with the Las Vegas shooting the focus will now turn to the motive for the shooter. Police surrounded an address listed for Devin Kelley in New Braunfels, near San Antonio on Sunday night. The First Baptist Church may also aide investigators - it tapes each weekly gathering and uploads the results to YouTube, meaning that the shooter may have been caught on tape.

Kelley was previously a member of the US Air Force, according to Air Force spokeswoman Ann Stefanek.

Kelley served in logistics readiness at Holloman Air Force Base, New Mexico from 2010 until his discharge, she said. The Air Force did not provide a date or condition of the discharge.

Investigators will be searching all social media related to the gunman, and his communications to try and discern why the attack took place. The attack will also no doubt open debate in Congress and beyond about gun crotrol, whether the weapon used in the attack was obtained legally or not.