ANNOUNCER: This is CNN breaking news.</s>BERMAN: All right, the breaking news, a deadly stabbing attack at Paris police headquarters. CNN's Nick Paton Walsh joins us now with the details. Nick, what have you learned?</s>NICK PATON WALSH, CNN SENIOR INTERNATIONAL CORRESPONDENT: John, things have changed substantially since we last spoke. We are now talking about a total of five dead from this attack, including the attacker. The five dead are all police officers, as far as we understand at this point. I say police officers. We are led to believe the attacker is, in fact, an administrative officer who works inside that police headquarters. And, in fact, police union secretary has been quoted on our affiliates BFM TV as saying that, in fact, that attacker may have worked there for 20 years or so. I say there, within French police. This occurring right in the heart of police headquarters in Paris on the Ile de la Cite right next to Notre Dame, the ruins of that after the fire earlier on this year. We're right at the heart of sort of tourist frequented Paris. It's in lockdown now. Many ambulances on the scene. And a startling rise in the death toll, John.</s>BERMAN: All right, Nick, please keep us posted. We're going to have much more on the breaking news ahead. And also a key witness arrives on Capitol Hill. That's next.
Stabbing at Paris Police Headquarters.