By the time it was all over, Cardona's pregnant granddaughter and 3-year-old great-granddaughter were hospitalized in critical condition and another young relative was dead of a gunshot wound to the head.
Authorities on Thursday charged a 19-year-old gang member, Brandon Taray Barnes, with murder and attempted murder in the shooting and said he had opened fire in retaliation after a male resident of the home had intervened earlier in the day when he saw the suspect hitting a woman outside a nearby market.
Barnes fired at least a dozen bullets into the mustard-colored home in a downtrodden neighborhood of this desert city 60 miles east of Los Angeles, police Lt. Gwendolyn Waters said.
Nylah Franco-Torrez, 3, was pronounced dead after the Monday shooting. Police declined to release the names of the surviving victims, but Cardona identified the pregnant woman as her granddaughter, 21-year-old La Donna Howie, and Howie's daughter, Justine Aguilar.
The man who intervened, angering Barnes, was Howie's husband, she said.
"My granddaughter's husband, he tried to help the woman and for helping her, this is what happened," she said. "Sometimes, you can't help everybody, especially if you don't know what the person is like."
District Attorney Michael Ramos called the shooting "horrendous" and a "cowardly act," and vowed justice in the case.
"We will not allow this to happen to our citizens, especially our babies," he said.
Barnes was arrested just after 5 p.m. Wednesday while riding his bicycle two blocks from the crime scene. Police have not recovered the weapon.
He could make a first court appearance as early as Friday, and it was unclear if he had retained an attorney.
Court records did not list an attorney for him, and a public defender who represented him previously, Andrew Moll, did not immediately return an email sent after business hours.
Police and prosecutors declined to release Barnes' photograph, saying they needed to protect the integrity of the investigation.
Howie was to be released from the hospital Thursday but would need extensive therapy to restore her voice and speech after being shot in the jaw and neck, Cardona said. Howie, who is five months pregnant, learned Wednesday night that her daughter was also hospitalized and learned Thursday that Franco-Torrez had died.
The relationship between Howie and Franco-Torrez was unclear.
Howie's daughter, who was also shot in the head, is in a medically induced coma because of brain swelling, Cardona said.
She is responding to people by moving her hand, authorities said.
"I went to see her yesterday and we were only allowed to go in and just look, not speak, not hold onto anything, make any noise to disturb her because she can hear you," Cardona said. "We're just hoping that it will all come out. I'm just hoping we don't have to go through another one."
Court records show Barnes had an outstanding warrant for his arrest on a misdemeanor charge of loitering by a school. He was arrested on allegations of fighting in a public place a year ago, but the case was dismissed after Barnes struck a plea deal.
The attack was one of four shootings in San Bernardino between Monday night and Tuesday morning and marked an end to more than two months without a homicide in the desert city 60 miles east of Los Angeles.
Authorities do not believe the victims or the man who intervened in the assault have any gang connections.