90% of contribute ptripoli. one of his three captured sons has escaped. let s he get the late frst from libya and sara sidner. first tell me what s going on there in zawiya. reporter: we were hearing a lot of loud booms, a lot of what sounded like mortar fire. there was definitely small arms fire. it sounded like this was a firefight and we went and checked it out. and we think that we have confirmed, we ve only talked to one of the rebels who has not been down at the square, but we think that it is again celebratory fire. but what they re using are things like anti-aircraft missiles. so it is very loud. it s hard to tell what exactly is going on. then we started hearing ambulances. we know zawiya has been under the control of rebels for about three days and we know that this has been a place that has been relatively rid of gadhafi forces for that period of time. and they ve pushed all the way into tripoli from here. but it is disconcerting when you start seeing tracer fire