DECATUR, Ga. -- DeKalb County police are investigating a double shooting in which a father appears to have shot and killed his 1-year-old daughter and then killed himself.

DeKalb County police officer Marcus Hodge says Mario Roberts, 21, was arguing with his child's mother in the couple's car when he pulled out a gun and shot their daughter, Amari Roberts. It appears the father then shot himself, Hodge said.

Officials said they were visiting the child's maternal grandmother's home to celebrate Easter. "They were over here visiting them and they were in the driveway when this occurred," said Hodge.

Police say the father and child were rushed to separate hospitals. The girl was later pronounced dead.

The father was also pronounced dead early Monday morning.

Hodge says investigators have been talking with the child's mother, who witnessed the shooting and is cooperating. Police told Channel 2's John Cater an argument ensued in front of the home and the father shot the baby girl, who was strapped into her car seat in the back of the vehicle, before shooting himself.