It is no surprise that Tiffany Burris was distraught Wednesday. Her 3-year-old son, Tyaan, was among those confined to the Precious Babies day-care center in North Philadelphia for hours while a gunman was locked in a standoff with police nearby.

“I couldn’t stop crying and shaking,” she said. “Bullets have no name on them.”

But mass shootings in the United States are causing stress and behavioral changes for millions who are not directly impacted, suggests a national survey conducted just days before six officers were shot in North Philadelphia.

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One in three adults said they agreed “strongly” or “somewhat” with the statement “Fear of a mass shooting prevents me from going to certain places and/or events,” according to the nonprofit American Psychological Association, which commissioned the poll in the wake of the shootings in El Paso, Texas, and Dayton, Ohio.

One in five adults said they “often” or “constantly” experienced stress from the possibility of a mass shooting, though the responses varied by race or ethnic group. The proportion that reported such stress was highest among Hispanic adults, at 32%, followed by 25% of blacks/African Americans and 15% of non-Hispanic whites.

“We don’t have to experience these events directly for them to affect us,” said Arthur C. Evans Jr., chief executive officer of the psychology organization and a past commissioner of Philadelphia’s Department of Behavioral Health and Intellectual disAbility Services.

Asked if they allowed fear of a mass shooting to change how they lived, 24% of survey respondents said they strongly or somewhat agreed.

And 32% said they agreed strongly or somewhat with the statement “I can’t go anywhere without worrying about being a victim of a mass shooting.”

The online survey was conducted on behalf of the psychological association by the Harris Poll between Aug. 8 and 12. Responses from the 2,017 participants were weighted as necessary to match the age, sex, and other demographic traits of the nation as a whole.