President Donald Trump says “there will be very serious retaliation” after two U.S. service members and one American civilian were killed in an attack in Syria that the United States blames on the Islamic State group. Trump said Syria’s president was “devastated by what happened” and stressed that Syria was fighting alongside U.S. troops. The two servicemembers killed were members of the Iowa National Guard, according to a person briefed on the situation who was granted anonymity because they did not have permission to speak publicly. U.S. Central Command said three service members also were wounded in the ambush Saturday by a lone IS member in central Syria. Trump said the three “seem to be doing pretty well.” The U.S. military said the gunman was killed.