On Monday, a judge determined that the dog was dangerous. But immediately after returning from court, investigators said Delserro armed himself with two handguns, went to his neighbors' house and opened fire.
There were six people in the house at the time.
"They all came home from court and then the suspect armed himself and went to the victim's house," St. Lucie County Sheriff Ken Mascara said at a news conference, per WPTV.
He said it was the little girl who made the 911 call, before she herself was shot.
"If you heard this call come over the radio, it would make the hair on your neck stand," Mascara said. "A little girl calls in saying: 'there's someone shooting in our house. I think our parents are dead. I think our family is dead.'"