A police officer died after being shot by a man who was being detained inside a police station in south London, Scotland Yard has said.
The sergeant was shot dead overnight by the man who had been brought into the Croydon custody centre, police said, and the gunman then shot himself at about 2.15am.
Paramedics treated the officer at the scene in Windmill Road before he was taken to hospital by the London ambulance service. He died in hospital.
A 23-year-old male suspect was also taken to hospital and remains in a critical condition.
In a statement, Scotland Yard said: “At approximately 02.15 on Friday 25 September the officer was shot by a man who was being detained at Croydon custody centre in Windmill Lane.
“Officers and paramedics treated him at the scene and he was taken to hospital by London ambulance service. Very tragically he subsequently died at hospital. We are in the process of informing all of the officer’s family and are supporting them with specialist officers.
“A 23-year-old man was detained by officers at the scene. He was also taken to hospital with a gunshot wound and remains in a critical condition.
“No police firearms were discharged during the incident.”
It remains unclear why the suspect was arrested and the Independent Office for Police Conduct will now launch a separate investigation into the circumstances of the officer’s death.
The Met police commissioner, Cressida Dick, said officers were now supporting the police sergeant’s family, describing the incident as “truly shocking”.
“When a colleague dies in the line of duty the shockwaves and sadness reverberates throughout the Met and our communities,” she said. “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.”
It is understood that at this early stage, lines of inquiry include the suspect’s mental health, why he had a firearm on him and why he opened fire.
The incident is not thought to be terrorism-related although Scotland Yard’s counter-terrorism command was monitoring developments.
The prime minister, Boris Johnson, tweeted: “My deepest condolences go to the family, friends and colleagues of the police officer who was killed in Croydon last night. We owe a huge debt to those who risk their own lives to keep us safe.”
Priti Patel, the home secretary, expressed her shock at the incident. “My thoughts today are with his family, friends and policing colleagues in London and across the country,” she said.
“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.”
The mayor of London, Sadiq Khan, said he was devastated by the news.
“I was informed of this tragic incident by the commissioner this morning,” he said, “and my heart goes out to the family of this brave officer, who has paid the ultimate price for helping to keep Londoners safe.
“Tragic incidents like this are terrible reminders of the dangers our police officers face every single day they go into work to keep Londoners safe. They are the very best of us, and I remain in close contact with the commissioner to offer her and the Met my ongoing support.”
The Labour leader, Keir Starmer, tweeted: “Horrific to hear of a police officer being shot and killed in Croydon. Our police put themselves in harm’s way every day to keep us safe. All my thoughts are with the officer’s family, friends and colleagues.”
Ken Marsh, chairman of the Metropolitan Police Federation, said: “The murder of a colleague on duty is utterly devastating news. Officers across London are in shock and sick to their stomachs at the nature of his death.
“All our thoughts – and that of all our members – are with his family, friends and close colleagues at this time. We and all members of the police family across the country are all utterly heartbroken at this news.
“Officers put themselves in danger every day to protect the public. Sadly, on very rare occasions officers make the ultimate sacrifice whilst fulfilling their role. When that happens we will ensure their bravery and sacrifice is never forgotten.”
The National Police Chiefs’ Council chairman, Martin Hewitt, added: “It is another tragic reminder of the risks police officers take on a daily basis to keep the public safe.
“Policing is a family and I join my colleagues across the country in mourning the senseless death of one of our own in the line of duty.”
Steve Reed, the Labour MP for Croydon North, tweeted: “All of us in Croydon are in shock at this heartbreaking tragic news.”