KABUL, Afghanistan — Five American troops died Saturday in bombings in southern Afghanistan where international forces are stepping up the fight against the Taliban, officials said.

Four of the victims died in a single blast, NATO said in a statement without specifying nationalities nor providing further details. A fifth service member was killed in a separate attack in the south, NATO said.

U.S. officials confirmed all five were Americans. The officials spoke on condition of anonymity under rules regarding casualty identification.