Mr. Trump wasn’t the only politician to trip over the details. On Sunday night, former Vice President Joseph R. Biden Jr., who is running for the Democratic presidential nomination, misstated the locations of both shootings.

At a fund-raiser, Mr. Biden referred to “the tragic events in Houston today and also in Michigan the day before,” according to a pool report. Michigan is to the north of Ohio, and Houston is about 700 miles from El Paso. Mr. Biden later corrected himself, according to the report.

For his part, Mr. Trump walked offstage Monday morning without taking questions from reporters or acknowledging his mistake. It was not immediately clear if the president had been improvising or reading the teleprompter script. A transcript of his remarks released later by the White House showed the phrase “in Toledo” struck through.