"Five crime scenes, four people deceased, one injured," said Northern Territory's Chief Minister Michael Gunner at a press conference. The territory's Police Commissioner Reece Kershaw said at the same press conference that one male was being held in custody in hospital, but had not been charged.
According to eyewitnesses, the gunman walked into the Palms Motel on Darwin's Esplanade and opened fire with a pump-action shotgun in a number of rooms before 6 p.m. They told ABC News that the gunman was looking for someone called "Alex".
The suspected gunman, aged 45, was later arrested, national broadcaster ABC News reported.
Kershaw said the suspect was "well known to the police" and had been released on parole in January. The suspect was believed to have been wearing an electronic monitoring bracelet at the time of the shootings.
Kershaw said the four deceased were all males and a woman had non-serious injuries to her leg.
Prime Minister Scott Morrison said on Twitter: "We have seen a terrible act of violence take place in Darwin this evening."
Witness Leah Potter said a woman was shot multiple times in the legs at the Palms Hotel.
"A man came running with a woman in his arms from next door, which is the Palms Motel the motel next to my motel and he just dropped her on the footpath right in front of us. I ran and got some towels and wrapped up her legs. She had little holes all in her skin on both her legs and she was bleeding," Potter said.
Another witness, John Rose, told The Australian newspaper he saw the gunman walk into the motel with a sawn-off shotgun. "He shot up all the rooms and he went to every room looking for somebody and he shot them all up. Then we saw him rush out, jump into his Toyota pickup, and rush off," Rose said.
According to Australian news site news.com.au, the police were treating the the Palms Motel as the main crime scene, but had also cordoned off a social club less than a mile away.
( With inputs from IANS )