Never enter a collapsed structure unless first responders indicate it is safe to do so.
Never approach downed or hanging power lines when a structure collapses as they could be charged (live) and you could be electrocuted. Stay back at least 33 feet (10 metres) from wires or anything in contact with them. Report electrical hazards to the police and the utility company.
If possible, shut off natural gas/propane lines to damaged building.