(CBS News) January 16 2019 12:58 PM U.S. troops were among those killed in an attack in northern Syria Wednesday -- the same day that Vice President Mike Pence said ISIS which claimed responsibility for the attack has been defeated. The U.S.-led coalition in Syria Operation Inherent Resolve said a tweet that U.S. service members were killed during an explosion while conducting a routine patrol in Syria today. A U.S. military official also confirmed to CBS News senior national defense correspondent David Martin reports by Kurdish media outlets that at least two Americans were among the dead in the city of Manbij not far from the Turkish border after an explosion hit a coalition convoy. The U.S. military has not said how many Americans were among the bombing victims but at least one report said as many as four U.S. service members were killed. If true Martin notes that it would be the single largest loss of U.S. life in Syria since American forces were deployed there in 2015. The attack comes just weeks after President Trump declared ISIS defeated and said U.S. troops were coming home. Speaking to a gathering of U.S. ambassadors at the State Department on Wednesday after the Pentagon confirmed the deaths of American troops in Syria Pence repeated both of Mr. Trumps assertions.