ATLANTA, Georgia (AP) -- A 17-year-old boy was arrested Friday and charged with killing his mother, who was a sheriff's deputy, and his two small sisters, authorities said.

Anthony Tyrone Terrell Jr. was charged with murder in the shooting deaths at the family home near Lawrenceville, where the bodies were found late Thursday, said police spokeswoman Illana Spellman.

She identified the victims as Gwinnett County Sheriff's Deputy Joy Deleston, 39, and her two daughters, Micaiah, 11, and Jelani, 4.

The motive for the killings was still under investigation, Spellman said.

Terrell was taken to jail in neighboring DeKalb County to avoid any potential conflict because Deleston worked for Gwinnett County, Spellman said. He is being held without bail.

Spellman said she could not confirm whether Deleston's service weapon was used in the fatal shootings or if investigators recovered the gun used in the killings. She said she did not know if there were any prior police calls to the home.

Deleston, a seven-year veteran of the department, was assigned to the Sex Offender unit, officials said.

Police had gone to the subdivision because a caller reported shots had been fired, officer David Schiralli said earlier. They found a bullet hole in a house, then checked next door because they knew a deputy lived there.

"There was no answer, but lights were on," Schiralli said. "They opened the door a little bit to announce themselves." That was when they discovered the bodies, he said.

The 17-year-old son arrived at the house about 35 minutes later, he said. Spellman said he was arrested after talking to investigators, but didn't elaborate.

Jeff Beaird, who lives across the street, said he often saw Terrell in the driveway shooting hoops with his friends or washing his mother's patrol car but doesn't remember anything out of the ordinary.

"It's so shocking because you don't expect something like this to happen," Beaird said.

Michael Hunt said he was taking a nap before starting work on the night shift Thursday when he heard the news about his neighbors. Hunt recalled that his wife had seen Terrell hours earlier walking down the street carrying a basketball.

"For him to be scared of our dog and then to kill his whole family ... it just doesn't add up," Hunt said.