the fighting echoing all around us. israel pounding the area for days. hamas militants fighting back. >> small arms fire, so be careful. >> reporter: a bulldozer cleared the way. these rescue workers going down the street, banging on doors, calling out for the wounded, clearing one house and then moving on to the next. then, frantic digging. a wounded man pulled out from under his house that collapsed. it's scenes like this that have triggered a u.n. investigation into war crimes. each side here accused. the u.n. says nearly 75% of the almost 700 palestinians killed here were civilians. israel says it's targeting militants and accuses hamas of using innocent people as human shields, itself a war crime, while more than 2,000 rockets have been fired from gaza into israel. two israeli civilians have been killed, while more than 30 soldiers have died. secretary of state john kerry is back in cairo after spending a day in israel, pushing a cease-fire deal and leaving empty-handed.