Thirteen American service members screening Afghans desperate to fly out of the country died Thursday in a suicide bombing at the Kabul airport in Afghanistan. President Joe Biden called the military members heroes, representing the best of America, working selflessly to help others escape the Taliban regime that has retaken the country. They were part of the bravest, most capable, most selfless military on the face of the Earth," Biden said. "And they were part of simply what I call the backbone of America. They're the spine of America, the best the country has to offer." The blast took place at the Abbey Gate as would-be evacuees were searched, leaving scores dead and injured. An Afghan offshoot of the Islamic State took responsibility. Biden vowed retribution, saying, "We will hunt you down."