Oscar Stewart of Rancho Bernardo, was the one who screamed at the suspect, 19-year-old John Earnest, and ran him out. Nick Oza (ozan), Arizona Republic
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SAN DIEGO – Before Saturday, John T. Earnest was known only as a quiet, successful student and an accomplished pianist.
On Sunday, his church reeled, calling a special session to address the news: Earnest had been detained in connection with Saturday’s deadly synagogue shooting near San Diego. 
His name had also been linked to a racist online posting that praised mass shooters, spoke of a plan to "kill Jews," and extensively cited scripture. 
Police had apprehended him along Interstate 15. A rifle was found in the front passenger seat, police said. 
Earlier, one woman was killed and three others wounded when a gunman wielding a AR-style assault weapon entered a synagogue during Passover services at the Chabad of Poway temple and opened fire.
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The suspect, a 19-year-old student at Cal State University San Marcos, is a part of a family known as regulars at the Escondido Orthodox Presbyterian Church.
The suspect’s father, John Earnest, is listed as an elder. Pastor Zach Keele said Sunday the younger John always came with his family but was very quiet.
Officials have said they found a "manifesto" posted online around the time of the attack and are working to verify its authenticity.
"I did not want to have to kill Jews," an online text reads in part. It is attributed to a poster by Earnest's name. "But they have given us no other option. I’m just a normal dude who wanted to have a family, help and heal people, and play piano."
It goes on to use repeated slurs and lists Adolf Hitler as an inspiration. It mockingly requests that its author be called a "white supremacist" and "anti-Semite."