A man swung a sword and pointed a crossbow at police during a break-in before he was shot, an investigation has found.
Convicted stalker Bryce Hodgson confronted officers before being shot in the neck and chest on January 30 at a property in Bywater Place, Rotherhithe, south-east London, the Independent Office for Police Conduct (IOPC) said.
A provisional post-mortem examination report last month found Hodgson died from gunshot wounds to his neck and chest.
Hodgson was handed a 16-week suspended jail term in July last year and put under supervision for 12 months after admitting stalking.
Officers were called to the property after several reports of Hodgson, who was carrying three crossbows, trying to force entry.
Hodgson had entered the home via the back door and was trying to get into a bedroom where the residents had barricaded themselves in, the IOPC said.
He was trying to break through an internal door using a sword when officers entered the property.
Hodgson, from Sheffield, was instructed to "show his hands" by officers who challenged him with a Taser, but he failed to comply and swung the sword at them.
The officers were then joined by armed support and firearms officers entered the property at 5.15am.
Hodgson did not follow instructions before picking up a crossbow and pointing it at an officer, at which point one officer then fired two shots hitting Hodgson in his neck and his chest, the IOPC said.
The weapons were secured, first aid was given and an ambulance was called by officers but Hodgson was declared dead at 5.37am.
Investigators have viewed body-worn video footage, obtained statements from the officers and listened to 999 calls and the officers' radio communications to establish what happened.
All of the officers who attended the incident are being treated as witnesses.
The IOPC said it had met Hodgson's family and expected to conclude the investigation in the summer.
IOPC regional director Mel Palmer said: "I send my condolences to the family and friends of Bryce Hodgson and all those present or affected by this tragic incident, including the occupants of the property and officers involved.
"The evidence gathered to date supports the officers' accounts that they perceived there to be an immediate and serious threat to the occupants inside the house.
"The officers, who were presented with a dynamic situation, acted swiftly to gain entry into the house to prevent any further harm to the residents."