Investigations are continuing into the death of Metropolitan Police Sergeant Matiu Ratana who was shot dead by a handcuffed suspect at a south London custody suite.
Known as Matt to his family and friends, 54-year-old Sgt Ratana, who was originally from New Zealand, joined the force in 1991.
He died in hospital after the 23-year-old gunman opened fire at Croydon Custody Centre in south London in the early hours of Friday.
The suspect, who had been arrested for possession of Class B drugs with intent to supply and possession of ammunition, also shot himself during the incident at about 2.15am and is in a critical but stable condition in hospital.
No police firearms were fired and the case is not being treated as terror-related.
A murder probe has been launched and investigators from the Independent Office for Police Conduct (IOPC) watchdog attended the scene.
The IOPC have obtained CCTV from the custody centre as well as body-worn video footage from the officers present.
These will now be reviewed in the coming days, and initial accounts from the officers present will also be taken.
The suspect was arrested by regular officers following a stop and search, then handcuffed behind his back before being taken to the station in a police vehicle.
The IOPC said he was taken into the building and sat in a holding area in the custody suite, then opened fire while still in handcuffs as officers prepared to search him with a metal detector.
IOPC regional director Sal Naseem said: "It is at that 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."
Met Commissioner Dame Cressida Dick, who with the Mayor of London, Sadiq Khan, led police officers across the capital in a minute's silence on Friday, described Sgt Ratana as a "talented police officer".
He 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 said.
Forensic officers in white suits were seen entering the police station on Friday morning, while floral tributes were left throughout the day.
Forces across the country flew flags at half-mast as a mark of respect and tributes poured in for Sgt Ratana, who Dame Cressida Dick described as a "lovely, lovely, much-respected police officer".
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.
They were murdered by Dale Cregan in a gun and grenade attack while responding to a report of a burglary in Greater Manchester.
The Met sergeant is the 17th from the force to be killed by a firearm since the end of the Second World War, according to the National Police Memorial roll of honour.
Unarmed Pc Keith Palmer, who was stabbed in March 2017 by terrorist Khalid Masood during the Westminster Bridge attack, was the last Met officer to be killed in the line of duty.
The roll of honour includes Pc Andrew Harper, who died when he was caught in a tow rope and dragged along country lanes after trying to stop quad bike thieves in Berkshire in August 2019.
The Thames Valley Police officer's three teenage killers were cleared of murder but convicted of manslaughter after an Old Bailey trial.
His widow Lissie Harper, who is campaigning for a change to the law which would see all those convicted of killing emergency workers receive a life sentence, said: "This is devastating news.
"No person should go to work never to return. No human being should be stripped of their life in a barbaric act of crime.
"Another hero has been taken from us in unwarranted violence."