The suspects have been identified as Marcus Anthony Eriz, 24, and Wynne Lee, 23, both of Costa Mesa. The two are expected to be arraigned in Orange County on Tuesday.
The exact details of the charges have not been determined, but it is believed the Lee was the driver and Eriz was the gunman. The vehicle, a white Volkswagen, has been recovered, as has a weapon.
"There are few words to describe the feeling produced by the despicable actions of that day," CHP Assistant Chief Donald Goodbrand said at a Monday afternoon news conference.
Officials held a news conference Monday to discuss the arrests on the same day Aiden was buried in a private ceremony, following a memorial service held over the weekend.
The more than two-week manhunt came to an end Sunday with the arrest of Eriz and Lee at their home in Costa Mesa, according to the California Highway Patrol. They are expected to be charged with murder and are being held on $1 million bail each.
Aiden was killed May 21 while his mother was driving him to kindergarten. The boy was sitting in a booster seat on the right rear passenger side when someone in another vehicle opened fire between 7:55 and 8:15 a.m. on the northbound 55 Freeway between the 22 Freeway and Chapman Avenue.
Aiden was rushed to Children's Hospital of Orange County, where he was pronounced dead.
Authorities say there was a tremendous outpouring of support, and a flood of tips from the public on the case.
Orange County District Attorney Todd Spitzer said the case resonated with the public in part because all Southern Californians drive the freeways.
"It could've happened to any one of us," Spitzer said. "We all drive the freeways of Southern California. We've all gotten upset at other motorists. Other motorists have gotten upset at us. I've thrown some gestures about myself.
"But it's never come to a situation of violence and certainly not in my realm or your realm, to the loss of a life."
Officials have released few details about the circumstances that led to the suspects' capture. 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.
White Volkswagen seized from Whittier home
The investigation led them to a home in Whittier, where they found and seized a white Volkswagen matching the description of the suspects' vehicle.
Neighbors of the home say they believe Eriz' grandmother lives there.
"It's kind of insane knowing that somebody five houses down the street was involved in this heinous crime," said neighbor Dave Kampa.
Aiden Leos case: Corona auto body shop owners describe suspected shooter as former employee
Eriz' Instagram page displayed videos that show him shooting various types of firearms on a range.
A married couple that owns Platinum Collision, an auto body shop in Corona, described Eriz as a former employee who stopped working at the business in January.
"His Instagram page is false," said Tom Gregg, referring to the suspect's social media page that suggested he still worked at the shop.
Gregg and his wife, Stephanie Gregg, condemned the fatal shooting, which she described as "devastating," and expressed their condolences to Aiden's family. "To have any kind of link is just too much," Stephanie Gregg said.
They added that Eriz recently sent a text, just a week after the shooting, asking if there were any positions open at any of the company's locations, and saying he also knew an office manager looking for a position.
Community groups and local government agencies contributed to a reward fund that grew to at least $500,000 to find the suspects.
On Monday, CHP officials said they weren't prepared to discuss whether any reward money will be paid out after the arrest of the two suspects.
"Three families have been unnecessarily torn apart and a beautiful little boy is now gone, all over a lane change," said county Supervisor Katrina Foley. "We must demand justice and accountability for such hate and lack of self-control."
A poignant memorial service was held Saturday afternoon at Calvary Chapel Yorba Linda.
'Mommy, my tummy hurts': Aiden Leos' sister describes little brother's final moments
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 that can be found here and here.