A long-serving police officer shot dead in a custody centre in south London has been named as Sgt Matiu Ratana.
New Zealand-born Sgt Ratana, known as Matt, was shot in the chest in Croydon as a suspect, who was still in handcuffs, was being checked in.
Met Commissioner Dame Cressida Dick described the 54-year-old as "talented officer" who was "big in heart".
After the shooting at about 02:15 BST the suspect, 23, is then thought to have shot himself.
The Independent Office for Police Conduct (IOPC) said the man was arrested on suspicion of possession of Class B drugs with intent to supply and possession of ammunition.
He is currently in a critical condition in hospital.
The IOPC confirmed he was handcuffed with his hands behind his back and had been taken to the custody centre in a police vehicle, before being escorted into the building.
The shots were fired as officers prepared to search the suspect, who was still handcuffed, with a metal detector, the IOPC said.
"A non-police issue firearm, which appears to be a revolver, has been recovered from the scene. Further ballistic work will be required," said IOPC regional director Sal Naseem.
A minute's silence was held at 16:00 BST at New Scotland Yard and Croydon Police Station to pay tribute to Sgt Ratana, who was heavily involved in rugby coaching when he was not working.
He would have been eligible for retirement in just two months.
"Matt spent very nearly 30 years as a uniformed police officer serving the public of London," said Dame Cressida.
"He will be remembered so fondly in Croydon and missed there, as well as in the Met and the rugby world," she said.
She added that he "leaves a partner and he leaves an adult son from a previous relationship. Our thoughts are with them."
Sgt Ratana joined the Met in 1991, having moved to the UK in 1989.
He was originally from the Hawke's Bay area of New Zealand and was educated at Palmerston North Boy's High School's, a town north of the capital, Wellington.
He served in various parts of London including Hackney and Selhurst, with his last posting as custody sergeant in Croydon, where he managed suspects who are brought into the cells.
"He worked in our detention command at Croydon but frequently volunteered for duty in custody suites across London," Dame Cressida added.
Sgt Ratana had led rugby teams in Worthing, close to Goring-by-Sea where he then lived and in East Grinstead, where he was living when he died.
Ryan Morlen, assistant head coach at East Grinstead Rugby Club, described him as "an absolutely lovely bloke".
"He is a bloke who is just so passionate about what he does - it does not matter whether you're the most talented or least talented, he will treat you equal," he said.
Earlier, BBC home affairs correspondent Danny Shaw said it was believed the suspect was known to counter-terrorism police.
He had been referred to the anti-extremism "Prevent" programme, though the Met said the murder inquiry was not being treated as terrorism-related.
The Met said a murder investigation was under way, but the shooting was not being treated as a counter-terrorism incident.
Dame Cressida said she understood "the great concern about how this happened" and that officers "will establish the facts".
"We owe it to Matt, his loved ones and all other officers. But we need to give investigators space to do their job," she said.
London's Mayor Sadiq Khan earlier said the police were currently "reviewing the safety of custody suites" and "there could be changes very soon".
Police officers and members of the public have been arriving at Croydon Police Station during the day to lay tributes.
The owner of a gym in Lancing, Sussex, told the BBC how Sgt Ratana had helped when his business was going through financial difficulty.
Neil Donohue, 54, said: "He came in one day and gave me 200 quid out of the blue, I said no no, I can't accept that and gave it back to him.
"But the next day he wired it into my account. That's the sort of guy he was."
A number of police officers have been turning their social media profile pictures black with a blue stripe to pay their respects.
John Davies, a retired officer who worked with Sgt Ratana when he was based in Hillingdon, said he was "a truly remarkable, strong and unique individual" who "left an impression on all those he came into contact with".
East Grinstead RFC also released a tribute to their "much-loved" head coach.
"Matt was an inspiring and much-loved figure at the club and there are truly no words to describe how we are feeling," said Bob Marsh, the club's chairman, and the club's president Andy Poole.