Whangarei gunman barricaded house, stashed hand grenades and firearms inside

A man whose shooting spree killed two women in Whangarei on Wednesday had spent the last two weeks barricading his house up, with a stash of weapons inside.

Quinn Patterson allegedly shot dead Wendy Campbell, 60, her daughter Natanya Campbell, 37, and wounded a contractor as they were conducting a property inspection at Patterson's rented house in Whangarei Heads.

After a day-long standoff with police, a fire started at the property with Patterson inside. He did not survive.

Badly burnt human remains were recovered from the property on Thursday evening, which police believe belong to Patterson.

The gunman's best friend, Ross Thompson, says Patterson learned he was going to be evicted two weeks ago, which is when he started "boarding up his place".

"He has steel bars [across the windows]... everything."

Mr Thompson, who helped Patterson with his maintenance company doing painting and water blasting, says the killer had acquired a huge stash of weapons using fake names.

"There were grenades, hand grenades. They were loaded," he said.

"He had shotguns... over 1000 rounds for the shotgun. Two-hundred rounds for another shotgun, a rifle, and he had a handgun... about four of them."

Mr Thompson says Wendy and her daughter - who had keys to the rental - had visited the property previously, which angered Patterson who wanted to remain in the house.

"He lost it mate. He was not happy they had keys to open the doors."

Patterson, who had previous convictions, hadn't had work for three months and was in financial strife. It wasn't the first time he had used violence.

"He had an issue with one of the boys at [an] auction and out of the blue put his hand around his neck, strangling him - I had to pull him away," a former co-worker told Newshub.

Mr Thompson says he regrets that his friend never found the help he needed.

"I feel sorry for the ladies but I also feel sorry for Quinn... because I've known him a very long time.

"He should have asked for help or something."

But help never reached Quinn Patterson - and now multiple families are grieving and planning funerals.