HERMOSILLO, Sonora — Four gunmen opened fire on a group of migrants as they crossed the border into the United States, wounding a Mexican man in the arm, police said. Rosario Porpe Sosa, 24, crossed back into Mexico after the shooting Tuesday and was hospitalized in Caborca some 40 miles south of the border with Arizona, Sonora state police said in a statement. His condition was not immediately known. The migrants had entered the United States at Sasabe, a common crossing point for people heading north illegally. Authorities did not give details about the attackers or a possible motive. Gustavo...