here's what new york city mayor bill de blasio had to say. >> when incidents occur such as the one in london last night, we put our special units such as a critical response command, on key duty at locations around the city, particularly well traveled, particularly prominent, all relate to the attack that was undertaken. that means new yorkers today will see a heavier presence at key locations around the city. you will see a stronger police presence including our counter-ter are forces. >> martin, this is not something unusual, this is something we have seen far too often unfortunately in recent years. >> you're right about that. we also know people take to social media to communicate. a lot of celebrities have been talking about this as well? >> that's exactly right. we have had tweets from oprah and mariah carey offering condolences and the we also had