Victims of a double homicide in downtown Winnipeg earlier this week were members of the same street gang, and shot and killed each other, police say.

Anthony Brian Cromastey, 30, and Rodney Albert Kirton, 25, died after opening fire on each other inside Johnny G's, a popular late-night restaurant and pub on Main Street, around 1:30 a.m. CT Wednesday.

"The investigation has determined the deceased males died as a result of simultaneous gunshots to each other," said a Winnipeg police spokesperson, Const. Rob Carver, on Friday.

Carver said both handguns have been recovered.

Investigators used surveillance video and witness accounts to conclude guns were fired at the same time, said Carver.

"So the two individuals were basically in a gunfight in a public restaurant and shot each other fatally on the spot," he said.

A simultaneous double homicide is "incredibly rare," Carver said. The police spokesperson said he was unaware of one ever happening in Canada before.

"We did a bit of research and it looks like it's happened in the [United] States once or twice, " he said.

About a dozen people were in the restaurant at the time, with many running out and flagging down a police cruiser that happened to be passing nearby.

A female server was hurt by a ricochet bullet and sent to hospital where she was treated for a non-life-threatening injury and released.

Carver said he's surprised there weren't more casualties because there were a lot of bullets flying.

Both men known to justice system: police

Cromastey and Kirton were members of the same street gang, but Carver wouldn't say its name.

"I never announce the gang. I'm not going to give any gang the publicity."

Criminal records show both men were familiar with the justice system.

Cromastey breached a bail order in 2013. At the time, he was not allowed to possess a cellphone. Kirton served time in jail twice for possessing drugs and was banned from possessing firearms.

Immediately after the shooting Wednesday, another man at the scene assaulted Kirton, police said. An 18-year-old was charged with assault for that attack.

"Kirton was still alive when the assault took place," Carver said, noting he and Cromastey were rushed to hospital in serious condition where they died shortly afterward.

Their deaths are the city's fourth and fifth homicides of the year.