(KTLA) — A 12-year-old boy was killed and an 11-year-old girl is hospitalized after an ATV hit-and-run incident in Apple Valley, California, over the weekend.

Close family friends Jacob Martinez and Christina “Tina” Bird were on a trip to California’s High Desert with their families, as part of a yearly Fourth of July tradition.

The two children were riding on the same ATV when they were struck around 9 p.m. Saturday.

Martinez and Bird were found lying next to each other. Jacob was pronounced dead at the scene, and Christina was placed on life support at Loma Linda Children’s Hospital after suffering several broken bones and a severed spinal cord.

“We were just trying to be with our families,” said Daisy Montano, Martinez’s aunt. “It was right in front of our campsite. We had no control of what was going to happen.”

The families shared photos of the severely damaged ATV on which the children were riding.

“My nephew was mangled. He was trampled to death,” Montano said through tears. “And that person just left. He left. Tina’s fighting for her life.”

California Highway Patrol is investigating the incident and believes the suspect’s vehicle is a bright orange, off-road 2021 RZR Turbo S or Turbo S4.

The families are demanding that the person responsible to come forward.

“Whoever you are, stop being a coward and do what’s right and step forward,” Martinez’s father said. “If you know who did this, please report them. If you are related to this coward, please report them.”

Family members set up GoFundMe pages for Martinez’s funeral and for Bird’s medical expenses.

“Jacob, daddy loves you very much, and we won’t stop until we get justice,” the boy’s father added.