Family members have identified a 6-year-old boy shot and killed in an apparent road rage attack as his mother drove him to school, as authorities continue to search for those responsible.

Aiden Leos died in his mother’s arms on the 55 Freeway in Orange on Friday morning, a relative wrote on an online fundraising page set up to help cover his burial costs.

“He said, ‘Mommy, my tummy hurts,’” his sister Alexis Cloonan, 15, said at a news conference recorded by ABC7. “So she went and she picked him up and he was bleeding on her; she had blood on her clothes.”

Someone had shot into the back of the family’s Chevy Cruze sedan, hitting the child from behind, investigators said. He was rushed to nearby Children’s Hospital, where authorities confirmed that the boy had died.

“We’re never going to be whole again,” Cloonan said. “He was amazing, and I hope that they know what they took today.”

The child’s mother was driving in the northbound lanes with her son in a booster seat near West Chapman Avenue around 8 a.m., California Highway Patrol officials said.