The first sign something was very wrong came just a few minutes before the bloodshed began.
Former Air Force member and Bible studies teacher Devin Kelley was seen driving through Sutherland Springs in his white SUV dressed all in black, in full combat gear.
The 26-year-old had a black mask on with a white skull on it and a bulletproof vest. At his side was a rifle. He was ready for battle.
His target was his mother-in-law who he thought could be inside the small First Baptist Church alongside a group of unarmed men, women and children going about their Sunday morning prayers.
In fact, his mother-in-law was not there. But it did not stop the killing.
US President Donald Trump put the blame squarely at the "domestic" situation, calling Kelley "deranged". But in Kelley's hand was an AR-15 style semiautomatic weapon he'd easily obtained even though his dishonourable discharge from the Air Force - because of domestic violence - should have prevented him owning a gun.
At 11.20am he parked outside a petrol station across the road from the church, got out with his gun and walked determinedly towards the church. He fired the first of his shots at this point.
What followed in the next few seconds changed the town's history.
Once inside police say Kelley "moved around freely" - there was nothing or no one who could stop his killing spree. Investigators are still trying to piece together what exactly happened. From the facts that are presently known, we know that 23 people died inside the small church. Many of them had no chance to try and escape, and they had nothing to shield themselves from the bullets.
A small girl, aged eight, is known to have hidden behind the pews in a desperate attempt to hide.
Two bodies were found outside. Police are trying to determine at what point the pair were killed. Was it as they tried to run for their lives? Or were they the first victims, as Kelley marched into the church?
One more person died at hospital, taking the toll to 26 dead.
The sound of the massacre was loud enough to alert Stephen Willeford's daughter. She walked into her 55-year-old father's room at his home down the road and told him she could hear shooting - coming from the church.
He told ABC affiliate KHBS: "I kept hearing the shots, one after another, very rapid shots - just 'pop pop pop pop' and I knew every one of those shots represented someone, that it was aimed at someone, that they weren't just random shots."
Willeford went to see what the commotion was.
Although he had no military background himself but was a former NRA instructor and was known throughout the small town as a good shot.
He told KHBS of the moment he laid eyes on the killer.
"He saw me and I saw him. I was standing behind a pick-up truck for cover."
He added: "I know I hit him. He got into his vehicle, and he fired another couple rounds through his side window. When the window dropped, I fired another round at him again."
He managed to hit Kelley in the side through a gap in his body armour, causing the killer to drop his gun and flee in his SUV.
It was at this point another man, Johnnie Langendorff, drove through Sutherland Springs to pick up his girlfriend. Willeford was barefoot and he signalled for Mr Langendorff to pull over.
"He jumped in my truck and said, 'He just shot up the church, we need to go get him.' And I said 'Let's go'."
Langendorff later told Good Morning America: "It seemed everybody had headed up to the church. I'm not sure if anybody really realised that he had left and gone that direction."
Neither man panicked. "It was an act now, ask questions later kind of deal."
Langendorff, 27, who is from nearby Seguin, pursued the car at more than 140km/h until the mass shooter crashed. Willeford told police he approached the SUV after he noticed Kelley hadn't moved.
Willeford cautiously approached the SUV, his weapon trained on Kelley.
He yelled, "get out of the truck, get out of the truck," but there was no movement.
In his eyes, he is no hero. "I think my God, my Lord protected me and gave me the skills to do what needed to be done," he said.
Inside the SUV the man who had slaughtered 26 people - from an 18-month-old to a 77-year-old - and wounded 20 others had himself died from being shot, by suicide.
In the frantic few minutes between the deaths of the innocent people and taking his own life, Kelley managed to call his father one last time.
In the brief call, and as Willeford and Langendorff pursued him, he told his father "he wasn't going to make it".
Soon after there was one more shot and the danger for Sutherland Springs was over. The nightmare, though, was only beginning.