Orange, California — Two people were arrested Sunday in connection with a road rage shooting that took the life of 6-year-old Aiden Leos on May 21.

The California Highway Patrol said Marcus Anthony Eriz, 24, and Wynne Lee, 23, were taken into custody outside their home in Costa Mesa, CBS Los Angeles reports. The CHP said it expects murder charges to be filed against them. CBS L.A. cites sources as saying the suspects are boyfriend and girlfriend.

Sources close to the case told the station they were being held at the Costa Mesa Police Department on $1 million bond.

Law enforcement officials told CBS L.A. they know where the suspects’ vehicle and the gun used in the shooting are, and they were trying to secure the firearm.

Orange County District Attorney Todd Spitzer said authorities were using search warrants in Costa Mesa to gather more evidence, CBS L.A. said.

The reward for information leading to the arrest of a suspect or suspects has soared past $450,000. There was no word on whether anyone will receive the money.

Leos, who was laid to rest Saturday, was riding in a booster seat in the backseat of his mother’s vehicle, on his way to kindergarten, when the shooting occurred. He was hit in the abdomen.

His mother, Joanna Cloonan, and the people in a white Volkswagen station wagon, allegedly Wynne and Eriz, got into the road rage incident over “a perceived unsafe lane change” on the 55 Freeway in the city of Orange, according to the CHP.

Investigators had been watching the two suspects and followed them from a restaurant before arresting them, CBS L.A. reports.

“These individuals had been under surveillance, and so at some point, we knew they were together in a restaurant today. It was a decision that was made today that that obviously wasn’t a safe place to make the arrest,” D.A. Spitzer told the station.

Cheryl Gish, an Orange County resident, heard news of the arrest and came with her husband to a makeshift memorial site for Aiden on an overpass above the freeway.

“I’m thankful that they have somebody in custody. It doesn’t bring the little boy back, little Aiden’s gone, but I’m so thankful some justice will be served,” she remarked to CBS L.A.