ORANGE, Calif. (KTLA) — A 6-year-old boy was shot and killed during an apparent road rage incident on a California interstate Friday morning, and the gunman remains at large, according to the California Highway Patrol.

The child was sitting in a booster seat in the right rear passenger side of his mother’s car when he was struck by the gunfire on the 55 Freeway in Orange around 8:10 a.m., according to CHP Officer Florentino Olivera.

Family members identified him as Aiden Leos. A GoFundMe campaign was set up to raise funds for his family.

His sister Alexis Cloonan said the boy’s mother is “not doing well, because it’s every mother’s worst nightmare. She had to hold him while he was dying.” 

He was transported by the Orange Fire Department to Children’s Hospital Orange County, where he died. Authorities have not identified the victim.

“It’s unfortunate we lost a boy this morning. Our thoughts and prayers are with the mom and the family,” Olivera said.

A witness who had pulled over to the side of the freeway to help the mother told the Los Angeles Times it appeared a bullet had entered the vehicle through the left side of the trunk.

“It went through the boy’s back,” Reyes Valdivia said.

The mother was “hysterical” as she pulled the little boy out of the vehicle after he had been shot, the witness recounted.

An off-duty police officer stopped at the scene soon after and performed CPR on the child, Valdivia said.

While CHP hasn’t released details about the road rage incident, Valdivia told the Times that the mother said she and her son were headed to school when a car cut her off as she tried to exit the carpool lane. She gestured to the two occupants — a man and a woman — and was exiting the lane when the gunfire erupted, according to Valdivia.

The shooter is believed to have been in a white sedan, but authorities do not have a detailed description of the car or suspect.

Olivera described the road rage incident as “isolated” and said it was unrelated to a string of more than 60 BB or pellet gun shootings that have been reported in Orange, Riverside and Los Angeles counties in the past three weeks, mostly along the 91 Freeway. 

CHP is pleading with witnesses to come forward, particularly anyone whose vehicle is equipped with a dash camera and was traveling on the northbound 55 between the 22 Freeway and Chapman between 7:55 a.m. and 8:15 a.m.

“If you were driving by, you saw something that was not right, call it in, even it wasn’t something major, call our office,” Olivera said.

Anyone with information about the incident is urged to call the CHP’s Santa Ana office at 714-567-6000.