Transcript for 4 Americans killed, 3 troops injured in Syrian terror attack

And we begin with four Americans among the dead after a horrific attack in Syria. The deadlyist attack in U.S. Forces since American troops went into Syria. Tonight, ISIS naming the bomb ebb. And we warn you, the images are difficult. A security camera on the city street actually recording the blast. Two people can actually be seen falling there. Miraculously, those people hit would get up. They survived. But at least 16 others were killed. Including those four Americans, two of them U.S. Service members, also a contractor and a worker with the defense department. And the attack comes just weeks after president trump declared ISIS had been defeated and called for all U.S. Troops to leave Syria. ABC's Terry Moran leading us off tonight. Reporter: The deadly attack caught on security camera video. A busy downtown street, then, a massive fireball. Victims crumple to the ground. A few stagger out of the smoke. The target, a restaurant wrecked by the blast, blood staining the walls, debris littering the street. Four Americans killed, two active duty service members, a civilian defense department employee and a contractor. Helicopters evacuated the injured. At least three other American troops were wounded in the blast. The Americans were "Conducting a local engagement," U.S. Officials say, in the strategically crucial town of M manbij, in northern Syria, where U.S. Troops have been on the ground for two years. Within hours, ISIS claimed responsibility. This attack comes less than a month after president trump's stunning announcement that he was pulling U.S. Troops out of Syria because, he claimed in a video he tweeted out, ISIS was defeated. We have won against ISIS. We've beaten them and we've beaten them badly. Reporter: And today, even after the attack in manbij, vice president pence stuck with that line. The caliphate has crumbled and ISIS has been defeated. Reporter: On capitol hill, the administration boasting about Syria, blasted as premature and even reckless. Trump ally senator Lindsey graham suggesting the president is, in effect, daring ISIS to kill Americans. It should set in motion enthusiasm by the enemy we're fighting. I hope the president will look long and hard about what we're doing in Syria. Clearly the senator speaking to the president directly there on television late today. Terry Moran with us live from the white house. And Terry, any response from the president tonight? Reporter: Not yet, David. We have heard from him on Twitter, but not on this subject, and the press secretary Sarah Sanders has issued a statement from the white house, saying our deepest sympathies and love go out to the families of the brave American heroes killed today in Syria. We also pray for the soldiers who were wounded in the attack. And she adds, our service members and their families have all sacrificed so much for our country. David? Terry Moran leading us off tonight. Terry, thank you.

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