WAYCROSS, Ga. -- A Waycross mother said her son was killed by what she thought was just a toy.

Mitchell "D.J." Maxwell, 11, was shot with a .177-caliber pellet gun at the Albany Avenue home of his football coach. He was transported to Satilla Regional Medical Center, where he died.

Felicia Thomas told Channel 4 her sixth-grade son was at a sleepover with two other boys at the coach's home when he was shot.

Ware County Sheriff Randy Royal said the three boys were playing a PlayStation 3 video game when one of the boys picked up what he thought was an unloaded pellet rifle and pretended to shoot it, then handed it to a 12-year-old who apparently shot Maxwell in the chest from point-blank range.

After trying to stop the bleeding themselves, the children notified two adults watching television in the next room that Maxwell was hurt, but did not immediately say he had been shot.

Stacey Chavez, 35, called 911 while Thomas "Zach" Williams, 22, performed CPR until Ware County emergency medical services personnel arrived.

According to the police report, the paramedics didn't know the boy had been shot until they got to the hospital. They thought he was having an asthma attack.

In the 911 calls, the caller told the operator the boy was gasping for air and that he had a history of asthma.

"He's unresponsive but he's breathing," one of the callers told 911.

"Do you know if he has a history of asthma or anything?" the 911 operator asked.

"He's one of my football players, and his cousin's here now and says he does have asthma," the caller said.

An autopsy was scheduled to be performed on Monday at the Georgia Bureau of Investigation's Savannah office.

Royal said the case remains under investigation and the results would be turned over to the district attorney's office for review and any further action.

Maxwell's mother told Channel 4 on Sunday she could not believe her son was gone.

"I just thought the world of him. I was so proud of him," said Thomas. "I just looked forward to him growing up and becoming a man and really showing me what he's made of. I worked really hard on him."

Mitchell Maxwell Sr., D.J.'s father, said he's dealing with pain and frustration, still trying to come to grips with what happened to his son.

"I don't think he meant to kill him, but still you don't play like that," Maxwell Sr. said. "My child is gone. ... You shouldn't put a gun, whether it's a pellet gun, a real gun, whatever, to anybody and pull the trigger."