It happened just before 6 p.m. Sunday night at the intersection of Champlain and Shepherd in Northeast Fresno.
Eyewitnesses told Action News a woman driving a Ford Explorer ran a red light and slammed into the back of a Honda. The eight-year-old boy and his two siblings were inside the Honda.
Immediately following the crash, drivers stopped to try and help the young victims.
"I had ran over to the little boy that was on the side of the crash and I helped him calm down. He was worried about his mom and dad. It was horrible. Just a horrible scene," said Sheila Brookeshire.
One other vehicle was involved in the crash. The driver of that car was not hurt. Emergency personnel treated other patients for moderate injuries.
Fresno Police say at this point no one has been taken into custody.