Sgt Matiu Ratana, known as Matt, was “big in stature, big in heart, friendly, capable, a lovely man and highly respected by his colleagues,” and leaves behind a partner and adult son, Dame Cressida Dick said.
Dame Cressida said he joined the Met in 1991, adding: “He was a talented police officer, captain of his recruits training class.”
She said he first worked in Charring Cross before working in Hillingdon and Hackney. Sgt Matt was originally from New Zealand. He worked as a constable patrolling London’s West End before moving to Hackney, where he was promoted to sergeant.
The 23-year-old murder suspect, who is believed to have shot himself, is in a critical condition in hospital.
The Independent Office for Police Conduct, which is investigating due to a member of the public being seriously injured in police custody, said the suspect was in handcuffs when shots were fired.
IOPC regional director Sal Naseem said: “What we have established is that the man was arrested for possession of class B drugs with intent to supply and possession of ammunition.
“The man was handcuffed to the rear before being transported to Croydon Custody Suite in a police vehicle where he was escorted into the building. He remained handcuffed to the rear and seated in a holding area in the custody suite.
“His handcuffs remained in place while officers prepared to search him using a metal detector.
“It is at the point that shots were fired resulting in the fatal injuries to the officer and critical injuries to the man. A non-police issue firearm, which appears to be a revolver, has been recovered from the scene. Further ballistic work will be required.”
A murder probe has been launched and investigators from the IOPC watchdog were at the scene to establish how the gun got into the custody suite.
Speaking from the scene, where floral tributes were left throughout the day, a friend who played rugby with Sgt Matt described him as “an inspiration” who was looking forward to retirement.
The 27-year-old, who gave his name as Paul, said: “The man was a machine. He went from training with us last night to come to his shift work here in Croydon. He would do that week in and week out.”
Gareth Howard, Chairman of Worthing Rugby Footbal Club, also paid tribute to Sgt Matt.
“During his time at Worthing RFC, as a coach for the Azurians & Knights, he dedicated himself fully to the role and supported players both on and off the pitch”, he said.
“Matt’s passion and dedication to rugby was always at the forefront of his coaching and nothing was too much trouble.
“He was funny, energetic and inspirational and the rugby community has lost a great man.
“Our deepest sympathy and thoughts go out to his family, friends and colleagues at this devastating time.”
Community police officer Jacqueline Kufuor burst into tears after laying flowers, describing Sgt Ratana as “a lovely guy” and “the nicest man I have ever met”.
She said: “You never expect this to happen when you go to work. For him to have been in custody and for this to have happened, it is just so sad.”
Leroy Logan, a former Met superintendent, said there were questions to be answered around the circumstances which led to the shooting.
“How did that person come to be in the station, whether it’s in the yard or the building itself, and be able to produce a weapon, whether it’s on them at the time?” he told BBC News.
Sgt Ratana is the eighth police officer in the UK to be shot dead in the last 20 years and the first to be murdered by a firearm in the line of duty since Pcs Fiona Bone, 32, and Nicola Hughes, 23, in September 2012.