. >> the mystery has congressman eric spalwell calling for tighter scrutiny, asking the department of homeland secretary for assurances that every passport used in international travel whether to, or from the u.s. be checked against the interpol data base. >> san francisco officials are on the scene of a massive fire on tuesday. >> investigators could be foeb foekusing on one particular cause. >> yes. streets are still closed. firefighters still dousing hot spots. we're smelling smoke in the air. they're trying to find the cause of the fire and focusing on this corner of the building. this is devastating and shocking. >> this is the burned out rubble of what used to be a luxury apartment complex under construction. sky seven captured the fire fight as the six-story building crumbled >> i thought it's just crazy. it's just going giant. looked like, well, just burning up. >> firefighters still putting out hot spots and investigators searching for a cause. abc # news learned they're concentrating on the northeast corner of the building. observing the spot from a ladder truck because it's