A Metropolitan Police officer was shot dead in a south London custody centre, and a 23-year old man was detained at the scene.
The police officer was shot by a man being detained at Croydon custody centre in south London and died in hospital.
The gunman was also taken to hospital with a gunshot wound after he turned the gun on himself, and remains in a critical condition and is under police guard.
The Metropolitan Police stressed that no police firearms were discharged, so it remains unclear at this stage as to how a gun was able to pass through security and a police search.
The Independent Office for Police Conduct watchdog will now lead an independent investigation, and the Met Police will investigate the murder of the police officer.
Met Commissioner Cressida Dick said, “This is a truly shocking incident in which one of our colleagues has lost his life in the most tragic circumstances. My heart goes out to his family, direct colleagues and friends.
“We are currently supporting his family and also have a dedicated team providing support to the officers and those in the custody centre who witnessed the shooting.
“When a colleague dies in the line of duty the shockwaves and sadness reverberates throughout the Met and our communities. Policing is a family, within London and nationally, and we will all deeply mourn our colleague.
“We are in the early stages of the investigation and are still working to establish the circumstances surrounding the incident and we will provide further updates when we have them.”
Home Secretary Priti Patel said, “I am deeply shocked and saddened to learn that a Metropolitan Police Officer has been shot and killed in the line of duty.
“My thoughts today are with his family, friends and policing colleagues in London and across the country.
“This morning I spoke to Metropolitan Police Commissioner Cressida Dick to express my condolences and to offer whatever support is needed as this tragic event is investigated.
“This is a sad day for our country and another terrible reminder of how our police officers put themselves in danger each and every day to keep the rest of us safe.”