The suspects have been identified as Marcus Anthony Eriz, 24, and Wynne Lee, 23. They were arrested at their home in Costa Mesa, according to the CHP.
Aiden was killed May 21 while his mother was driving him to kindergarten. The boy was sitting in the right rear passenger booster seat when someone in another vehicle opened fire between 7:55 and 8:15 a.m. on the northbound 55 Freeway in Orange County.
The boy was rushed to Children's Hospital of Orange County, where he was pronounced dead.
Officials were releasing few details about the circumstances that led to their capture Sunday. But they have previously said a man and a woman were driving a white Volkswagen and it is believed the male passenger fired the shots that killed Aiden.
The California Highway Patrol released a photo of the suspect vehicle, described as a white 2018 or 2019 Volkswagen Golf Sportswagen with non-tinted windows and a sunroof. Officials believe the woman was driving the vehicle and the male passenger, who fired the weapon, was sitting in the front seat.
Community groups and local government agencies contributed to a reward fund that grew to at least $500,000 to find the suspects.
A poignant memorial service was held Saturday afternoon for Aiden.
The service at Calvary Chapel Yorba Linda was not open to the public to attend but was livestreamed for viewing online.
"This a a memorial, not a funeral," Pastor Joshua Holiday said. "A funeral's a ceremony, it's held in connection with the burial or cremation, someone's death and it signifies the end of their existence. A memorial service is a ceremony serving to preserve the remembrance of someone's life. The focal point is different."
"We're here to celebrate the life of Aiden," he added.
Joanna Cloonan, the boy's mother, eulogized her son in an emotional tribute. She opened her remarks by expressing gratitude for the outpouring of support from loved ones and strangers alike.
"Your kindness, your prayers, your support and unbelievable generosity has helped provide me with so much strength, so I may stand on my own two feet today, in front of you, and share the beauty of who Aiden was and still is," Cloonan said.
"The joy he brought into our lives was insurmountable," she said. "My heart melted every time he laughed."
In lieu of flowers, the family has requested that supporters make donations to assist the family through a pair of GoFundMe pages.