ORANGE, Calif. (KTLA) – The family of the 6-year-old boy who was killed in an apparent road rage incident on the 55 Freeway in Orange, California, last week is offering a reward for information leading to the shooter’s arrest as his mother spoke out for the first time about her devastating loss.

A reward of over $300,000 is now being offered after the Orange County Board of Supervisors voted to contribute, on top of the $50,000 put up by the family.

A GoFundMe account created to support the family has garnered more than $200,000 in donations as of Tuesday.

Relatives were initially raising money to pay for the child’s funeral and other expenses, but the campaign’s goal was updated on Sunday after the page reached its initial fundraising target.

Speaking publicly for the first time since her little boy was killed, Joanna Cloonan, in an emotional interview with ABC News, said she wants justice for her son, Aiden Leos.

Cloonan described him as beautiful, kind and precious. “He meant the world to me, and it feels like my life is over,” she said. “That was my baby. I’ve never, never thought pain like this could exist.”

Aiden died after being shot around 8 a.m. last Friday, a little more than a week after he celebrated his birthday.

He was sitting in a booster seat in the back seat of his mother’s car when he was struck by gunfire on the northbound 55 near Chapman Avenue in what is being investigated as a possible road rage incident, according to the California Highway Patrol.

“You killed him for no reason,” the grief-stricken mother said of the assailant, her voice choked with emotion.

Recounting the incident to ABC News, Cloonan said she was taking her son to school when a vehicle cut her off while she was in the carpool lane.

Relatives told KTLA she then made a gesture at the other car, which is believed to be a white Volkswagen station wagon.

Moments later, the suspect’s vehicle — which had two occupants, a female driver and a male passenger — pulled behind the woman’s car and fired at least one shot into the back of it, striking the little boy. He complained that his stomach hurt.

“As I started to merge away from them, I heard a really loud noise,” Cloonan told ABC News. “And my son said, ‘Ow,’ and I had to pull over. And he got shot.”

Cloonan’s daughter and Aiden’s older sister Alexis told KTLA her mother didn’t immediately recognize the noise as a gunshot “because no one would think that someone just shot a bullet into my car,” she said.

“It wasn’t until that she grabbed him and there was blood all over her clothes” that her mother realized what had happened, the teenager recalled.

The boy was rushed to a local hospital, where he was pronounced dead a short time later.

“It’s every mother’s worst nightmare,” said Alexis Cloonan. “She had to hold him while he was dying. No mother should have to go through that.”

The daughter reiterated that her mother hasn’t been doing well since Aiden was killed.

“She just keeps crying for him, ‘my baby, my baby,'” Cloonan recalled through tears. “She keeps yelling for him.”

Aiden’s father is also mourning the loss of his son and a GoFundMe page has been started on his behalf as well, according to Lacy.

“He’s equally devastated as the mother, unable to speak,” she told reporters on Sunday night.

The child’s killing has triggered an outpouring of support in the community, also evidenced — along with the donations — by the growing memorials that have been placed along the freeway and a nearby overpass in recent days.

“I just left Joanna, she looked me in the eye, and she said the outpouring of love that she has received — that I’m trying to tell her, all over the world … — she sat there in disbelief. That she cannot believe the love and support she’s getting around the world,” Lacey said. “Not as much as the disbelief that she’s experienced with this tragedy, but I would like to believe that it’s going to triumph.”

Meanwhile, the search for the vehicle and the shooter continues, with CHP asking witnesses to come forward, In particular, they are looking for anyone who may have dash cam or cellphone video that was taken on the northbound 55 near the 22 Freeway and Chapman between 7:15 a.m. and 8:15 a.m. last Friday.

The family hopes that the reward will spur people to action and help lead to the killer’s arrest.

“I hope that justice is served for Aiden, and that that person doesn’t sleep tonight, because we aren’t. They need to know what they took, it wasn’t just some kid,” Alexis Cloonan said.

Anyone with information is urged to call CHP’s Santa Ana office at 714-567-6000, or 800-TELL-CHP. Tips can also be emailed to Santaanachptipline@chp.ca.gov.