A man accused of killing a 21-year-old woman inside a Decatur apartment Saturday morning called 911 after the shooting, DeKalb County police said.  Carl Williams, 23, and the woman lived at an apartment complex in the 200 block of Glen Hollow Lane, DeKalb police Lt. Lonzy Robertson told The Atlanta Journal-Constitution in an email. The woman’s name has not been released pending notification of next of kin. MORE: Man charged with murder in 21-year-old’s shooting death “Investigators believe there was some kind of physical altercation between the two before the shooting,” Robertson said.  Williams called 911 about 10:30 a.m. Saturday after the shooting, police said. Investigators walked into the apartment and found the woman “with an obvious head injury” and “no signs of life,” according to the report.  RELATED: Cops: Estranged boyfriend threatened to kill postal worker a week before murder But Williams, according to arrest warrants, said the two were playing with a gun and he accidentally shot her.  Williams also told authorities he threw the gun in a creek, according to the warrant. Officials later found the weapon.  Police found and detained Williams, who remains in the DeKalb County jail without bond. No one else was in the apartment at the time, but detectives said a roommate arrived after they were already on the scene.   In other news: [Summary]