Police in metro Atlanta say they have arrested a woman who held her newborn grandchild hostage following a domestic argument.

Gwinnett County police Cpl. Michele Pihera said in a news release a four-hour standoff with a SWAT team ended peacefully Tuesday morning. She says the 4-week-old baby was unharmed and the child's grandmother, 57-year-old Laurie Morgan, was charged with aggravated assault and reckless conduct.

Police say the standoff began with a domestic argument at the Highland Corners Apartments, where Morgan grabbed the baby while holding a gun, then walked outside with the child and fired a gunshot.

Police dispatched a SWAT team, which hours later entered the apartment and arrested Morgan.

Morgan was booked at the Gwinnett County jail. It was not immediately known if she had an attorney.