As U.S. troops searched Afghans, a bomber in the crowd moved in

At 5:48 p.m., the bomber, wearing a 25-pound explosive vest under clothing, walked up to the group of Americans who were frisking people hoping to enter the complex. He waited, officials said, until just before he was about to be searched by the American troops. And then he detonated the bomb, which was unusually large for a suicide vest, killing himself and igniting an attack that would leave dozens of people dead, including 13 American service members…

Pentagon officials said they were still piecing together the chain of events that took place at Abbey Gate on Thursday. There will be after-action reviews and storyboards with detailed lists of what led up to that moment. There will be questions: Why were so many service members grouped so close together? How did the bomber evade the Taliban checkpoints? Did someone let him through?…

Just after the bomb went off, Defense Department officials said, fighters nearby began firing weapons. The officials said that some of the Americans and Afghans at Abbey Gate might have been hit by that gunfire. There was so much confusion in the aftermath of the explosion that the military initially reported that a second suicide bombing had taken place at nearby Baron Hotel. That turned out to be false, according to Maj. Gen. Hank Taylor, the Joint Staff deputy director for regional operations.