kuper kuper cupertino. >> reporter: the ex-please happened here. the gas migrated the home and traveled through to the garage where the gas pooled ant explosion hit with such force it blew off the garage door. >> people in kupertiyo started the day with a courtesy call. do you have to go under the house? >> no, ma'am. >> it's peace of mind for anyone living in the sho dough of this. a natural gas explosion and fire gut add condo. >> it sounded to me like a car crash. >> reporter: did you smell any gas before thing motion? >> no, there wasn't anything going on, really. it was a normal day. i was working. >> reporter: the force of the explosion blew off the garage door. pg&e is under a spotlight since last year's massive deadly explosion in san bruno. this week, the national transportation safety board released a report about that explosion. given pg&e's history, the ntsb and the california public utilities commission are also taking an interest in what's happened in kuper cuppertino this week. >> we are, thankful that nobody was hurt. we are here to answer any questions or concerns >> reporter: the explosion was caused bay buildup of natural gas in the garage. an investigation reveals six other leaks. >> it's concerning for us. we don't want to find leaks in our systems. we are committed to getting to the bottom of not only this community but other places. we want to make sure that everybody is safe. >> feels safe now because they checked everything. >> reporter: the door-to-door served two purposes. public safety and public relation. you are taking a live view from the mass cam. you can see that the fire went through the roof of the home. that's because, although pg&e workers went here shortly after the explosion, it took 90 month to shut off the gas line. that's because the works had to drill from three different locations in order to pinch off the lines and stop the flow of gas to this home. reporting live, noelle walker, ktvu ktvu. >>> michael hoff