American Drones Strike in Yemen and we begin with the breaking news. U.S. Officials tell abc news that after all the week on terror alert, the u.S. Targeted and hit four of the central players behind that threat. It's a fast-moving story, and our chief investigatorive correspondent brian roth has the details right now. There was a small by significant tie psy of relief from u.S. Counterterrorism officials today, with a senior official telling abc news that four al-qaeda terrorists connected to the latest threat stream against the american embassy in yemen had been killed in a drone strike over the weekend. Yemen has become the center of the latest al-qaeda plots against the u.S. And according to other u.S. Officials, about three dozen al-qaeda operatives have been killed over the last two weeks. But not among those killed is the master bomb maker who made the underwear bomb to bring down a u.S. Airliner. And last year, he designed a bomb that would have gone through screening machines undetected. It was discovered by an undercover agent and turned over to the cia. All our equipment that screens over a million checked backs in the u.S. Was not calibrated to detect that. The u.S. Agree remains closed, and the threat concerns are with al-qaeda are real and serious even with the tactical victory of the drone killings. The bottom line is, as a senior u.S. Official told us, we got the operational guys we were looking for. But not the master bomb-maker? He is still at large. Not considered to be killed or wounded, and very much a threat. And I'm sure they're on the hunt tonight. Thank you, brian. And now we turn to those floods all around this country