EL PASO — After 22 people were shot to death at a Walmart in El Paso over the weekend, a Florida retiree found herself imagining how her grandchildren could be killed. A daughter of Ecuadorean immigrants cried alone in her car. A Texas lawyer bought a gun to defend his family.

For a number of Latinos across the United States, the shooting attack in El Paso felt like a turning point, calling into question everything they thought they knew about their place in American society. Whether they are liberal or conservative, speakers of English or Spanish, recent immigrants or descendants of pioneers who put down stakes in the Southwest 400 years ago, many Latinos in interviews this week said they felt deeply shaken at the idea that radicalized white nationalism seemed to have placed them — at least for one bloody weekend — in its cross hairs.

“At least for Latinos, in some way, it’s the death of the American dream,” Dario Aguirre, 64, a Mexican-American lawyer in Denver and a registered Republican, said about the impact of the killings on him and those around him.

Mr. Aguirre moved to San Diego from Tijuana when he was 5, and was raised by his grandmother in poor Mexican neighborhoods. He enlisted in the Air Force, and later became an immigration lawyer — a classic American success story.