The intruders fled back across the border to Nogales, Mexico, after U.S. federal officers converged on a smuggling operation in progress Wednesday in Nogales, Ariz., the Los Angeles Times reported.
People on the Mexican side of the border began throwing rocks at the officers, who ordered them to stop. When they didn't, one of the assailants was shot, agents said.
The man fell next to a medical office.
The mayor of Nogales, Mexico, said the man had been hit by eight shots.
The officer was placed on administrative leave pending an investigation by the FBI.
Last month, a woman allegedly trying to run over an agent was shot and killed in a suburb of San Diego, and an alleged rock thrower was shot to death on the banks of the Rio Grande near Nuevo Laredo, Mexico, authorities reported.