For the second time in as many months, a North Side family was struck by tragedy after a 45-year-old woman shot outside of a local motorcycle hangout last weekend died of her injuries on Wednesday.

Candice Hackett, died at North Memorial Medical Center in Robbinsdale Wednesday morning of complications resulting from a gunshot wound to the head, according to Minneapolis police and relatives. She was the mother of 25-year-old Chad Robertson, who was fatally shot by an Amtrak police officer during an encounter in downtown Chicago.

According to police, Hackett was shot during an early-morning confrontation Sunday outside the Hell's Lovers Motorcycle Club, at 2629 Golden Valley Road — a popular hangout for bikers. She was taken to North Memorial, along with a man whom police say had been stabbed in the abdomen.

A third victim, a male with a gunshot wound, later showed up at the hospital, police said. Both men, ages 35 and 49, are expected to survive.

It was unclear what prompted the attack. Authorities have released few details, only disclosing that the investigation remains active. Sgt. Catherine Michal, a police spokesperson, said four detectives have been assigned to the slaying, the city's seventh of the year.

Several witnesses contacted on Wednesday said that an argument led to the shooting outside of the club. One woman said she heard a commotion outside, followed by "more gunshots than I could count." Like others, she declined to be identified out of fear for her safety.

Police say they arrested a man with a gun at the scene and booked him into county jail on suspicion of weapons possession. Another man, 21, was arrested in Robbinsdale after fleeing on a motorcycle, and a second handgun was recovered. Neither man was charged and both have since been released.

A spokesman for the Hennepin County attorney's office said Wednesday afternoon that police haven't presented a case for charging.

In social media postings this week, friends and relatives remembered Hackett as a loving, tough-minded matriarch who had held the family together after Robertson's death. Her husband, reached by telephone, declined to comment.

Robertson died Feb. 15 at a Chicago hospital after being shot the week before outside Chicago's Union Station. Prosecutors say that he was shot while running from Amtrak officer LaRoyce Tankson and his partner, who had stopped Robertson and two of his friends, apparently after catching them smoking marijuana.

Tankson was later charged with first-degree murder.

Authorities have said that they did not recover any weapons on Robertson, although they did find a small amount of drugs and cash at the scene. The day after he died, his family filed a federal lawsuit alleging excessive force and a violation of his Fourth Amendment right against unlawful search.

A protest and memorial

On Wednesday night, more than 100 people gathered outside the Union Depot in St. Paul to protest Robertson's shooting death and to memorialize his mother. Activist Mel Reeves said Hackett had been looking forward to the event, originally dedicated to honoring her son.

Family friend Maxine Maxon said hearing the news about the death of Robertson, and Wednesday about his mother, was "heartbreaking."

"I just saw her," Maxon said. "We are so hurt."

People who spoke about Robertson said he was loyal and a good friend. His mom was kind and had an impact in the community, others said.

Staff writer Karen Zamora contributed to this report.