Officials say one of the bullets bounced off the concrete hitting the boy.
Captain Christopher Bergner said in a press conference that he believed the shot that hit the child was a product of " skip" rounds that ricocheted of the ground, originally meant to hit the dog.
Bergner called the shooting an "extremely, extremely unfortunate incident".
'Our initial impression was [the deputies] didn't even see the individual coming around from the side of the building'.
The boy restrained the dog and took him to a carport area behind the home.
Armando Garcia was hanging out at a friend's apartment listening to music early Thursday morning when the dog started barking. The wounded animal then scuttled back to a carport area and deputies followed it to try and corral the dog. "At that point, two deputies engaged the dog in gunfire".
The deputy that was bitten by the dog was also struck by a ricocheting bullet.
He was rushed to a hospital where he was later pronounced dead.
The young man was frantically searching for Garcia-Muro's mother, Alcantar told the Los Angeles Times.
Deputies have responded to the location at least four times for loud music and gang activity in the past two months, the department said.
Five deputies were at the scene.
The owner of the dog, who told the Times she didn't want to identify herself because she had "too many things going on with the law right now", said she doubted the deputies' claim that the 3-year-old blue-nosed pit bull attacked them.
Robinson, whose daughter lives in the apartment complex near where the shooting happened, told KTLA she never witnessed the dog being aggressive.
The dog was eventually captured by the deputies and taken to animal control, who plan to euthanize the pit bull. "They are good kids".
She maintains that her dog was well behaved and that the deputies' description does not match the dogs personality. He was about 40 feet away and out of sight of deputies, investigators said. He would have been a senior at R. Rex Parris High School in Palmdale this fall. "He would give his life for anybody", she said.
- Qatar goes ahead with $12bn USA fighter jet deal despite Trump's criticism
- Kershaw wins, Bellinger hits 2 homers as Dodgers top Indians
- Donald Trump takes swipe at Obama on student death
- Cristiano Ronaldo to testify in tax fraud case July 31 - court
- Muslim girl may have been sexually assaulted
- Trump knows he is "being investigated for firing the FBI Director"
- White House paints Handel win as Trump triumph
- "The Mummy" and "It Comes at Night" top this week's new releases
- Spanish state prosecutor accuses Jose Mourinho of tax fraud
- Dead, missing toll in London fire rises to 79, police say