FRESNO, Calif. — The mother of an unarmed 19-year-old man shot and killed by police in a traffic stop is seeking financial damages from this central California city for her son’s death.

An attorney for Veronica Nelson filed a lawsuit against the city of Fresno and the police department Thursday. It says that officers used excessive force when they opened fire and killed her son, Dylan Noble in June. Officers stopped him in his pickup truck after getting a report of a man walking along a street with a rifle or shotgun.

Police Chief Jerry Dyer has said officers believed Noble was about to shoot them. They later learned he was unarmed.

Officers fired at Noble a total of four times, including the final round from an officer’s shotgun, according to the suit.

The city declined comment. A police department representative was not immediately available for comment.