The gunman who shot dead a Metropolitan Police custody sergeant in the early hours of today was allegedly having his temperature checked at the time as part of new booking rules amid the coronavirus pandemic. The detained man was said to have been about to be assessed and have his temperature and details taken after arriving at Croydon custody centre in South London following his arrest on suspicion of possessing ammunition. He shot the unnamed officer at about 2.15am this morning. Officers and paramedics then treated the officer - who was said to have been nearing retirement - at the scene before he was taken to hospital where he later died. The arrested man - who is still alive in hospital despite turning the gun on himself - had been arrested by a special constable with a normal officer on patrol after he was seen behaving strangely. They searched him and allegedly found ammunition on him, before handcuffing him and driving him in a patrol car to the custody centre. The custody sergeant is the tenth police officer to have been killed in the line of duty in the past decade, with the last being Andrew Harper in Berkshire in August 2019. PC Harper's widow Lissie Harper said on Facebook that it was 'utterly devastating', adding: 'What is happening to our world?'