Port-au-prince, Haiti—U.N. Secretary-General Ban Ki-moon visited victims of devastating Hurricane Matthew on Saturday, saying the destruction wrought by the storm was “heartbreaking,” and he renewed a pledge to help the nation cope with a deadly scourge of cholera that was introduced by U.N. peacekeepers. Ban’s brief visit came as victims of the storm continued to express frustration — sometimes violently — at delays in aid about a week-and-a-half since Matthew hit southwest Haiti with 145 mph (235 kph) winds, killing at least 546 people and demolishing or damaging tens of thousands of homes. “I met so many displaced persons, young people, women who were pregnant and sick people. It was heartbreaking,” he said, describing his tour of an emergency shelter in the town of Les Cayes packed with families whose homes were destroyed. Shortly before Ban’s helicopter was due to land in Les Cayes, a clash broke out between rock-throwing residents and peacekeepers at a U.N. base there.