in addition to those killed, more than 50 others were injured, sotme critically. now the question, what happened? pacific gas and electric says a 30-inch gas line,at s one that to 50 years old, likely ruptured. we are constantly working every day to make sure that we are maintaining the integrity of that system. reporter: as the investigation intensifies, people stunned in this community rocked by the disaster hope for answers. ntsb investigators will be analyzing a 30-inch pipe. they ll also look at maintenance records, its condition and the employees who were in charge of that, as part of their investigation. now, as for the residents, they re being told they re not allowed back into that blast zone, at least not for some time, until it s determined to be safe. alex? understandably so, given what we ve witnessed there. leanne gregg in san bruno, thank you. that florida pastor who inflamed muslims around the world by announcing his
putting out the fire without the supply being shut down. reporter: planes dropped retardant and by dawn, the fire was mostly contained. in addion to those killed, more than 50 others were injured, some critically. and now the questi, what happened? the local gas company pacific gas and electric says 30-inch gas line, one that s 40 to 50 years old likely ruptured. we are constantly working every day to make sure we re maintaining the integrity of that system. reporter: as the investigation intensifies, people stunned in this community rocked by the disaster hope for answers. now, as for those residents from those neighborhoods, there s no word yet on when they ll be allowed return and see what s left of their homes. alex? leanne, there have been some who have wondered why the national transportation safety board is leading this investigation. is it because of their vast experience with these major catastrophes like this? with plane crashes and alike? reporter: and because they