Six of the injured, including two police officers, were treated at Auckland Hospital after the Thursday morning attack in the city's CBD.
On Friday morning, Acting Superintendent Sunny Patel said police's immediate priority was to formally identify Reid's two victims.
"We can advise that the two victims were men aged in their 40s, who worked at the construction site alongside the deceased offender," he said.
"One officer remains in hospital in a stable condition, and one officer is recovering at home from their injuries."
Three others remain in hospital with non-life threatening injuries, while two were discharged.
Reid is also dead, but it is not yet clear whether he was killed by police or took his own life.
The NZ Herald reports he was sacked from the worksite the previous day.
The 24-year-old was serving five months' home detention, which in New Zealand allows offenders exemptions to visit worksites.
The sentence came from a 2021 incident when Reid assaulted and strangled his girlfriend.
After the woman escaped and phoned police, Reid lied about the attack before his conviction.
According to court documents reported by local media, a sentencing document revealed he had a "systemic depravation" in his upbringing, and as a child was exposed to family violence and abuse.
"All of that makes depressingly familiar reading to me, Mr Reid," Judge Steve Bonnar said at the time.
"I do not want to send a young man like you, with a limited history, to prison. I think it would be counterproductive and actually set you down the wrong path.
"But you need to realise, Mr Reid, you need to turn your life around from here because if you commit further offences of violence in the future, things are just going to get worse and you could well end up going to jail."
The incident has shocked New Zealand, with locals on their morning commutes describing running in fear at the terrifying moment Reid fired his pump-action shotgun on his way to the construction site.
Both police and the government have promised a probe into whether there were any leading indicators Reid was likely to escalate his criminality.
"The events of yesterday morning were incredibly traumatic for all involved and we know New Zealanders have many questions about what occurred," Mr Patel said.
"I can assure you that a large investigation team is working to provide answers to those questions, particularly for the families of the two men who lost their lives and the other workers caught up in this tragedy."
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