PALMDALE, Calif. — When a dog that had already bit one of them charged a group of deputies, two of them opened fire. Authorities say they did not see the teenage boy standing some 30 feet behind, who was struck down by a bullet that apparently bounced on the concrete and hit him in the chest.

The 17-year-old, who had helped to restrain the dog after the first bite, died at a hospital an hour later, turning what began as a mere early-morning noise complaint at a party in Palmdale into a freak tragedy.

The same Los Angeles County deputy that was bitten by the dog was also hit by a bullet fragment Thursday but survived. He was treated at a hospital and released.

The dog, which survived the shooting, was later euthanized.

The boy's mother, Roberta Alcantar, said his name was Armando Garcia-Muro, the eldest of four siblings about to start his senior year of high school. She said he loved dogs and planned to go into construction.

"He was a very loving person,"Alcantar told the Los Angeles Times.

Sheriff's Capt. Christopher Bergner called it an "extremely, extremely unfortunate incident," adding that it didn't appear the deputies saw the teen in the dark before they fired.

After the male pit bull first bit the deputy, Garcia-Muro restrained the dog behind the apartment complex that is also home to his mother, his aunt, and a neighbor who owns the dog. Then it broke loose and charged again.

Deputies shot and wounded the dog when it was about 10 feet away, then chased it as it tried to run back behind the building, officials said. Only then did they see that the boy, who had been standing about 40 feet away, had also remerged from behind the building and had been hit in the chest by a so-called "skip round" that had ricocheted off the pavement.

The deputies had first been called to the Palmdale complex at about 3:45 a.m. with complaints of a loud party.

Sheriff's officials said in a statement and at a news conference that they found evidence of several shots having ricocheted off the ground, and concluded that one of those most likely killed the teen.

They did not elaborate further, and a message left with one of the homicide detectives on the case was not immediately returned.