DAYTON, Ohio — On Sunday, Americans woke up to news of a shooting rampage in an entertainment district in Dayton, Ohio, where a man wearing body armor shot and killed nine people, including his own sister. Hours earlier, a 21-year-old with a rifle entered a Walmart in El Paso and killed 20 people.

In a country that has become nearly numb to men with guns opening fire in schools, at concerts and in churches, the back-to-back bursts of gun violence in less than 24 hours were enough to leave the public stunned and shaken. The shootings ground the 2020 presidential campaign to a halt, reignited a debate on gun control and called into question the increasingly angry words directed at immigrants on the southern border in recent weeks by right-wing pundits and President Trump.

“It’s outrageous,” said Terrion Foster, who works in accounting and lives in Kansas City, Mo., where he was out shopping at a farmer’s market near downtown on Sunday afternoon. “It’s really sad because I feel like you can’t go anywhere and be safe. I’m 50 years old and I didn’t think I’d be alive to see some of the things that are going on today.”

[For the latest updates, read our live briefing on the Dayton and El Paso shootings.]

The shootings prompted Republicans, including Mr. Trump, to condemn the gunmen’s actions and offer support to the people of Dayton and El Paso. Democrats urged Congress to take action and pass stricter gun laws. “We have a responsibility to the people we serve to act,” Speaker Nancy Pelosi said in a statement.