He was wearing all black tactical gear and a bullet proof vest as he shot people of all ages.
Twenty three people were found dead in the church, two outside and the 26th victim died after being transported to hospital.
The youngest victim was a five-year-old and the oldest a 72-year-old – but the death toll may rise, authorities have warned.
Kelley was chased off from the scene by a brave local resident who engaged him with a rifle, forcing him to drop his weapon and flee the scene.
He was later found dead in a vehicle, which had multiple weapons inside, but it’s not clear whether the fatal wound was self inflicted or as a result of the clash with the member of the public.
Kelley has been identified as a former member of the US Air Force with a military background.
The first confirmed victim is 14-year-old Annabelle Pomeroy, the daughter of the First Baptist church pastor Frank Pomeroy.
The couple were both out of town in two different states when they heard the tragic news.
Other tearful relatives of church goers gathered outside the building as they waited desperately to hear about their loved ones. Police have yet to officially confirm the names of any victims.
Witnesses reported seeing a man walk into the church at around 11.20am local time, half an hour into a Sunday morning service, before hearing gunfire ring out.
The church is thought to have a congregation of around 50, which would suggest more than half were slaughtered by the gunman.
Another church, just down the street, got word that their neighbours had been attacked while they were mid-service.
Phones and pagers began ringing as it became clear that there had been a shooting, one CBS reporter said.
As the pastor and other members of the congregation ran to assist their fellow place of worship, they were ‘met with a scene of carnage’ with reports suggesting numerous children had been involved in the atrocity.
Earlier, Peter Baker, Chief White House Correspondent for the New York Times said: “Texas county commissioner tells NBC News ‘there are a lot of fatalities’ at church shooting, estimating 24 dead. The shooter is deceased.”
Local news channel Kens5 Eye Witness News claims that a two-year-old is among the shooting victims.
A six-year-old boy is also believed to have been shot four times, and is now in hospital undergoing surgery, according to his uncle who spoke to CBS News.
The nearby University Hospital confirmed they had received four children but did not specify whether were deceased or injured.
US President Donald Trump has tweeted about the atrocity, and confirms he is currently monitoring the situation from overseas.
He wrote: “May God be w/ the people of Sutherland Springs, Texas. The FBI & law enforcement are on the scene. I am monitoring the situation from Japan.”
A US reporter in San Antonio wrote on Twitter: “At least six helicopters called to transport victims.
“Neighbours say they heard shooter may have reloaded multiple times, around 50 people usually at service.”
He added: “Police tell me shooter is dead and there is no more active threat.
“Area of the church is now blocked off and taped off. Family and friends still waiting to hear if their loved ones are safe.”
The Bureau of Alcohol, Tobacco, Firearms and Explosives , FBI agents and US Marshalls are all on the scene.
Greg Abbott, the Governor of Texas, said: “Our prayers are with all who were harmed by this evil act. Our thanks to law enforcement for their response. More details from the DPS soon.”
In a longer statement, he said: “While the details of this horrific act are still under investigation, Cecilia and I want to send our sincerest thoughts and prayers to all those who have been affected by this evil act.
“I want to thank law enforcement for their response and ask that all Texans pray for the Sutherland Springs community during this time of mourning and loss.”
Energy Secretary Rick Perry wrote: “Anita and I send our prayers to the victims of the shooting in Texas.”
Sutherland Springs is a small community located in Wilson County, Texas on US Highway 87, with a population of just 362, according to the Handbook of Texas, published in 2000.
It has a Post Office, two petrol stations and a Dollar General Store.
One man wrote on Facebook: “Unbelievable that people can’t go to church now without having to worry about an attack while praying.”
Another added: “A very sad day.
“Prayers to all involved that your Lord would comfort and strengthen this community in this terrible tragedy.”
Hunter Wallace said on Twitter: “What kind of country are we living in when sick people are shooting people worshipping at church? It has happened again in Sutherland Springs.”
The Boston Globe tweeted that today’s mass shooting is the 307th incident (with four or more victims) out of 309 days in the US. (Mirror)