Wilson County Sheriff Joe Tackitt said Kelley walked into the church and began shooting.
Kelley has a military background and was a resident of New Braunfels, a suburb of San Antonio. In the days before the massacre, he posted a picture of an assault rifle on his Facebook profile, with the caption: “She’s a bad b***h”.
A armed neighbour exchanged gunfire with Kelley after he left the church but then escaped in his vehicle, according to Johnnie Langendorff who witnessed the end of the shooting. Mr Langendorff said he and the man then chased Kelley for several minutes.
A local law enforcement official, Freeman Martin, told KSAT the neighbour who shot and chased Kelly saved lives and stopped more mayhem from happening.
Kelley was later found dead after going off the road in neighbouring Guadalupe County. It is not known if he took his own life or was killed by the neighbour.
Texas Governor Greg Abbott has confirmed the death toll is 26. About 20 others have been wounded.
The victims ranged in age from five to 72 years old. A pregnant woman was among the dead. Twenty-three were found dead in the church, two were found outside and one died in hospital.
A neighbour said the shooting happened when there were about 50 people at the service — if that number is correct then almost the entire congregation would have been killed or injured.
Clad in black and wearing tactical gear and a ballistic vest, Kelley pulled up at a petrol station across from the church about 11.20am. He crossed the street and started firing a Ruger AR assault-type rifle at the church, before entering the church and opening fire.
HORRIFIC DEATH TOLL
First Baptist Church Pastor Frank Pomeroy told US broadcaster ABC his own 14-year-old daughter Anabelle was among the dead. “She was one beautiful, special child,” he said.
He was not at the church at the time of the massacre. He believed “every one” of his family’s close friends had been killed.
In a separate interview his wife Sherri Pomeroy added: “My husband and I were ironically out of town in two different states. We lost our 14-year-old daughter today and many friends.”
Other victims included a six-year-old boy named Rylan who was in surgery after being shot four times, his uncle told CBS News. A two-year-old was also shot and wounded, according to the Dallas Morning News.
Horrific details are also starting to emerge about the young victims of the church massacre.
Four children from the same family have been shot, including a seven- and five-year-old girl. It wasn’t immediately known if those children were from the same family.
An eight-year-old is reported to have survived by hiding among the pews.
A local man, Nick Uhlig, 34, wasn’t at the service because he was out late on Saturday night — but he told Associated Press some of his cousins had been shot in the massacre.
He says the cousin who was killed had three children and was pregnant with a fourth. He didn’t know the conditions of his other relatives.
Meanwhile, friends, family and supporters were rushing to hospitals where the survivors had been taken to.
A young man standing outside the Brooke Army Medical Center in San Antonio, said he and his mother had been wounded in the shooting and that this father had been killed.
Amanda Mosel told the San Antonio Express her 13-year-old goddaughter was among the dead.
“From what I’ve heard, someone just walked in and started shooting,” she said.
MASSACRE: HOW IT UNFOLDED
Initially it was believed the shooter was killed after a brief chase north into neighbouring Guadalupe County but it is now unclear how he died.
“There was no police chase,” Guadalupe County sheriff’s spokesman Sergeant Robert Murphy told AFP, denying earlier media reports that the gunman was killed after a pursuit.
“He was in his vehicle,” Mr Murphy said, without adding any further details.
Authorities said a civilian with a gun confronted the attacker and chased him away.
Johnnie Langendorff told KSAT he witnessed the end of the shooting and said another man and Kelley exchanged gunfire after Kelley left the church. Mr Langendorff said he and the man then chased Kelley for several minutes in their vehicle.
A local law enforcement official, Freeman Martin, told KSAT the armed neighbour who shot and chased Kelly saved lives and stopped more mayhem from happening.
A witness said the gunman was dressed in what looked like combat gear when he burst into the church and began shooting during the Sunday morning service.
It is unclear if the shooter was killed by the resident or took his own life. His body was found alongside several firearms.
The Pentagon has confirmed that Kelley previously served in the Air Force.