so away from sfo, san francisco international airport. san bruno police put out a note saying that there is police activity, they're urging people to stay away from that area. the sheriff's department has confirmed they're responding to calls of an active shooter. clearly, a lot is going on right now, but as far as what's happening inside, we don't have detailed confirmed information about that at this point. nicolle? >> i no e we're not going to report anything until we've been able to corroborate it. this is the heart of stiilicon valley, one of the main players in the worldwide social media world. are there accounts that exist on social media that we simply can't talk about yet because they're not confirmed? >> right. at this point, nothing valely c confirmed by employees. we've seen a few employees who say they're inside the building, have come out. one basically saying they heard a lot of running. at first thought it was an earthquake because there was rumbling from the people running. another person says they did hear gunshots and ever since then, they've been barricaded