a loud bang. now, u.s. and uk officials believe that this is an ek pleegs fr explosion from a bomb. egyptian officials are saying it's too early to tell. it could be an engine exploding or battery exploding. they say they're not sure. we are hearing from u.s. officials that the federal bureau of investigation, the fbi, may lend some support to the egyptians to help determine what brought this plane down, and one example, they said, was that they could help them analyze the sound to determine what it is. there's still an ongoing investigation on the ground to find any sort of debris and evidence of the bomb there f. still at this hour, there's a lot of scrutiny about the security at egyptian airports. russia has a team on the ground here as well. not just in sharm el sheikh at the airport behind me but also