The Sheriff's Office in Jacksonville, Florida, said a 1-year-old boy was struck by a truck after falling out of an SUV.
Jacksonville Fire and Rescue Department was called to Arlington and Lillian roads after someone was hit by a car.
Police said a Chevy Tahoe was turning right when the left rear door opened and the 1-year-old fell out.
"She (the driver) had four kids with her," said JSO Sgt. Donald Washington. "Her 4-year-old daughter was in the front seat. She had her two nephews and her son in the back seat."
A Chevy Silverado traveling behind the Tahoe ran over the 1-year-old, police said.
The baby, who was not in a car seat, was taken to an area hospital with life-threatening injuries. Police said the mother claims the child was wearing a seat belt.
The child was among four children in the SUV without car seats.
"At this time, we don’t know how he got out," Washington said. "But it’s been said that he’s been known to open the back door."