CHICAGO (AP) — Even as the United States reeled over the massacre of 19 children and two teachers at an elementary school in Texas, multiple mass shootings happened elsewhere over the Memorial Day weekend. Single-death shootings still accounted for most gun fatalities, however. Police chiefs in Chicago and other cities cancelled days off to boost the numbers of officers over the holiday, hoping a heightened presence would be a deterrent. Some cities said they would strictly enforce curfews. The strategies may have worked in specific cases, but statistics from several cities didn’t indicate violence was kept at or below previous years’ levels. At least nine people were killed over the weekend in Chicago, up from three a year ago.