Police praised a 23-year-old hero mom Sunday and announced the death of a fourth victim in an Arkansas mass shooting in what officials have branded a "completely random, senseless act."

Ellen Shrum, 81, died Saturday of her wounds after the shooter, armed with a 12-gauge shotgun and pistol, began "firing indiscriminantly" at a Mad Butcher grocery store in the small community of Fordyce south of Little Rock, according to police.

Another victim was nurse Callie Weems, who had a new baby girl at home and stopped to aid a wounded shopper at the store when she was killed, police said.

"Instead of fleeing the store, she stopped to render aid in one of the most selfless acts I've ever seen," Arkansas State Police Director Mike Hagar said at a news conference Sunday.

The last conversation Weems had with her mom was to celebrate sleeping in until 9 a.m. the morning of the shooting for the first time since the birth of her baby girl, Ivy, 10 months ago, her mother, Ellen Browning, told the Associated Press.

"I bet you feel like a new mom," Browning said she texted back.

When Browning later tried to reach her daughter after news of the shooting "she didn't answer," Browing told KARK-TV.

Browning was also close to another victim, 50-year-old logger Rob Sturgis, whom she fondly described to the AP as "country as cornbread" and a loving dad to his daughter.

Also killed was Shirley Taylor, 62, who was described to KTHV by her daughter Angela Atchley, as the "rock" of her family b

The victims appear to all have been "targets of opportunity," Hagar said, with no relationship to the suspected gunman, 44-year-old Travis Eugene Posey of New Edinburg, who was arrested at the scene.

A total of 15 people, including Posey, were shot at the store, police said.

It was at least the third mass shooting at a U.S. grocery in the last three years, and the 234 mass shootings so far this year, according to the Gun Violence Archive.

Another mass shooting earlier this month at a Michigan splash park for kids that injured nine also appears to be a random attack, according to police.

Investigators have been unable to find any connection between the park and shooter Michael William Nash, 42, who was later found dead in a nearby house with an apparently self-inflicted gunshot wound.

A cache of 11 other guns were found in Walsh house. He reportedly had a history of mental illness and believed he was being tracked by the government.