Detectives said a 62-year-old woman was rushed to the hospital after her nephew beat her Saturday morning.
Investigators from Atlantic Beach Police and the Jacksonville Sheriff's Office said it happened at a home on West 13th Street near Mayport Road in Atlantic Beach.
They said a family was preparing for a garage sale when a man assaulted his aunt.
Nancy Waldron was taken to Shands Medical Center in critical condition.
Waldron's nephew was arrested and charged with felony battery causing great bodily harm. He is scheduled to make his first appearance in court Sunday morning.