>> reporter: police have put in a cordon two blocks now distance for us. since i've been here the last five or ten minutes we've seen four or five police support vehicle, ambulance support vehicles coming in, sirens blaring, not leaving the scene, which might suggest the situation is relatively under control. at the same time, the british home secretary, the interior minister, tweeted about 45 minutes ago the situation was, quote, ongoing. what we know from metropolitan police, and there's a lot of information out there, you heard from an eyewitness, a lot of people saw this, it happened in one of the most vulnerable central parts of london just at the peak of friday lunch hour, people perhaps going home early, out with colleagues. what we know, the 158 police were called to the premises in the area around london bridge. there appears to have been a stabbing there. emergency services attended and later on the police have gone on to say they are treating this incident as though it is terror