A police officer trying to detain a suspect has been shot dead, reportedly while taking the man's temperature.

While undergoing a standard coronavirus temperature check, the handcuffed suspect managed to pull a gun from his trousers and shoot the officer before turning the gun on himself, The Sun reports.

The Met Police officer was treated by officers and paramedics at Croydon Custody Centre in Windmill Lane, south London around 2.15am on Friday morning, September 25.

He was then rushed to hospital, where he was tragically pronounced dead.

A 23-year-old man was detained by officers and also taken to hospital with a gunshot wound after reportedly shooting himself.

He remains in a critical condition.

Forensic officers at the scene in Croydon Custody Centre in south London

Commissioner Cressida Dick said: “Today, we police are all mourning a great loss. I would like to thank our officers and the staff, together with colleagues from the London Ambulance Service, the London air ambulance and all our medical and hospital colleagues who I know did everything they could to save his life.

"A murder investigation is under way and officers are working at several crime scenes to secure evidence and to establish the facts of what happened. We are working closely with the Independent Office for Police Conduct.

"Early indications are that the suspect shot himself. This has not yet, of course, been established as a fact. The man, I can tell you, remains in a critical condition in hospital.

"I do understand that there is considerable interest in the identity of my colleague but I cannot tell you yet his name, as we have not yet been able to inform all of his close family."

Officers and paramedics provided first aid but the victim was pronounced dead in hospital

Officials are in the process of informing the officer's family.

Prime Minister Boris Johnson paid tribute: "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."

Home Secretary Priti Patel added: "I am deeply shocked and saddened to learn that a Metropolitan Police Officer has been shot and killed in the line of duty.

A 23-year-old man was detained by officers and also taken to hospital with a gunshot wound

"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."

Boris Johnson said: 'We owe a huge debt to those who risk their own lives to keep us safe'

Mayor of London Sadiq Khan tweeted: "Devastated by this news. 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."

In a statement issued on Twitter, the Met Police Federation, which represents 30,000 of London's police officers, said: "This is completely devastating news.

"Our thoughts are with our colleague's family, friends and close colleagues at this awful time, We are offering our officers our support."

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.

Sadiq Khan added: 'Tragic incidents like this are terrible reminders of the dangers our police officers face'

“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.

“Colleagues involved in the incident will have our full support for as long as is needed.”

Croydon Central MP Sarah Jones said: "Absolutely shocking news. I am speaking to the police on the details of this awful incident. My thoughts are with the family and colleagues of the officer killed."