A crazed gunman tried to hijack a water truck minutes after gunning down a four-year-old girl and her grandpa outside a Target store.
Ethan Blaine Nieneker, 32, was photographed by a passing motorist dramatically stealing the truck at a construction site in north Austin on Monday.
Leaning out of the cab, he balanced precariously on the step with one hand holding onto the door while the other clutched a handgun pointed at a worker.
Nieneker was wearing a Hawaiian shirt and fluorescent blue and yellow-patterned shorts in the photo as he tried to make a getaway on the Mopac Expressway.
Minutes earlier he allegedly shot dead Adam Chow, 65, and his granddaughter Astrid, 4, along with Target worker Hector Leopoldo Martinez Machuca, 24.
Adam was shot first as he sat in the driver's seat, as Astrid watched.
Nieneker is then accused of turning his weapon towards Astrid, shooting the little girl at point blank range as she sat in the back seat of her grandpa's car.
The shooter did not know either of his victims, investigators say.
Ethan Blaine Nieneker, 32, was photographed dramatically stealing a water truck during his getaway from a mass shooting at a Target in Austin where three people were killed.
Nieneker in his booking photo at the Travis County Jail, showing him staring straight at the camera with several fresh cuts on his face.
Astrid, 4, with her grandfather Adam Chow, 65, whom she called 'GongGong'. They were shot dead within seconds of each other by a gunman outside a Target in Austin.
After shoving Chow's wife Doris, 66, out of the family's grey Toyota 4-Runner, he took off away from the store before trying to switch cars to the water truck.
Stricken Doris pulled Astrid from the car in a bid to find help that could save her, but the youngster succumbed to her injuries shortly after.
He allegedly attacked the driver and tried pulling him out of the truck, but wasn't able to, instead chasing the truck driver away with his pistol before returning to the Toyota.
Chow's family said Astrid was deeply loved by her family, teachers, classmates, friends, and 'all who had the privilege of knowing her'.
'Sweet Astrid brought joy, laughter, and light to everyone she touched,' they said.
'Adam Chow was a loving husband to Doris; beloved father to Monica and Sophia; doting grandfather. He dedicated his life to loving God and loving others.'
Austin Police Chief Lisa Davis alleged at a press conference that Nieneker first 'randomly' shot Machuca about 2.15pm as he collected trolleys.
Austin homicide detective Nathan Sexton said Nieneker chose his victims 'completely randomly' and used a handgun given to him by a family member.
'He said that he was Jesus and there was no real reason whatsoever given,' he said.
After his aborted attempt to steal the truck, he crashed into a Volkswagen about 2.25pm, then allegedly attacked and carjacked the Volkswagen driver.
Nieneker only drove that car until 2.34pm when he tried to steal a self-driving Waymo car, but failed and got back in the Volkswagen.
Minutes later, a church acquaintance of Nieneker claimed a brick came flying through the window of his house on La Casa Drive after the gunman threw it.
Nieneker's alleged rampage continued until 2.58pm when he was spotted walking naked through a backyard down the street from the one he bricked.
He was seen running into a 'porta potty', then running away again before police found him, still nude and holding a Bible, and demanded he surrender.
When he refused, police fired their tasers and he was arrested at 3.06pm.
'The investigation shows that Nieneker conducted these violent offenses of shooting at multiple victims, killing three victims, and destroying multiple vehicles, in the span of less than one hour,' police said.
Chow was pronounced dead at the scene at 2.39pm and his granddaughter at 2.50pm. Doris only suffered minor injuries.
Nieneker was charged with two counts of capital murder for Chow and his granddaughter first-degree felony murder of Machuca.
His booking photo at the Travis County Jail showed him staring straight at the camera with several fresh cuts on his face.
Sexton said Nieneker gave no motive for the shooting and his state of mind at the time was still being investigated.
'We're still looking into the drug portion of it. He could have been under the influence of narcotics; it might not necessarily be all attributed to mental illness; so we're still investigating all of that,' he said.
Davis admitted there were failures by authorities to follow up on mental health callouts which may have prevented the shooting.
'This man had some serious issues; and I think about the systems that failed... there were some serious failures here,' she said.
Nieneker had two emergency mental health detentions of up to 72 hours in 2018 but was not committed either time.
How Nieneker got the gun which he left in Chow's car from a relative is being investigated and could lead to charges against his family.
'Where does someone with this capacity to do this get a weapon and when does a family members feel comfortable giving someone with these issues a weapon?' Davis said.
Nieneker lived alone and worked at a nearby restaurant, police said.
Davis said police received calls about the shooting 15 minutes after it began and rushed to the scene within four minutes.
Social media photos of Nieneker showed him grinning with friends at social events, posing while wearing a Covid-style mask by a trash bin, and posing beside a fireplace.
Another Facebook image showed the alleged gunman holding a large brown leaf in front of his face and creepily peering over it, and a fifth photo had Nieneker wearing an American flag as a bandana.
Davis told reporters on Monday evening that Nieneker has a history of mental illness and a prior criminal history on charges including drugs and assault.