CANBERRA, June 8 (Xinhua) -- The man accused of killing four people in a mass shooting in Australia's Northern Territory (NT) on Tuesday night has apologized for his actions.

Benjamin Hoffman, 45, on Friday appeared in Darwin Local Court via video link where he was formally charged with four counts of murder, two counts of recklessly endangering life and one of causing criminal damage.

Judge Elizabeth Morris extended an at-risk order, which was first put in place when he was arrested, after which Hoffman apologized.

"I'm very sorry for what's happened," he said.

"I do need help, I asked for help."

Police have previously confirmed that Hoffman was released on parole in January having served time in prison.

It is alleged that the 45-year-old opened fire with an illegal pump-action shotgun at multiple sites in Darwin's central business district and surrounding suburbs.

Four men were killed and a woman was wounded but has since been released from hospital.

Police are still investigating links between Hoffman and his alleged victims, three of whom have been identified as 33-year-old taxi driver Hassan Baydoun 57-year-old Michael Sisois and 52-year-old New Zealander Rob Courtney.

Coutney's son, Joseph, spoke to the Australian Broadcasting Corporation (ABC) about the impact that his father's death has had.

"The loss of my father's life has been a sudden and extremely traumatic experience," he said

"It is with deep sadness that we try continue in our day-to-day lives, not knowing whether or not at this stage we will be able to have a funeral and properly say goodbye to him.

"Our condolences go out to the other families suffering the loss of their loved ones in this cold, violent and senseless act that has robbed our beloved victims and their families of a future together."