A mother and son in a car were shot when a woman opened fire on them as they sat at a stop sign in Staten Island on Christmas, police said.

The 42-year-old mother was stopped at Highview Avenue and Fillmore Street in New Brighton, with her 19-year-old son in the passenger seat, when a black SUV pulled up behind them just before 3:30 p.m., cops said.

The mother was shot in the lower back while her son was shot in the left shoulder and grazed in the head. Both were taken to Richmond University Medical Center and were in stable condition.

The motive for the shooting was unclear, officials said.