LOS ANGELES (CBSLA) – Police arrested one driver and are searching for a second who struck and killed an 18-year-old USC student while he was walking along the 110 Freeway in South Los Angeles in the early morning hours Saturday.

An undated photo of Matthew Olson, who was struck and killed on the 110 Freeway in South Los Angeles on Aug. 23, 2019. (Credit: Corona Del Mar High Sea Kings Boys Basketball/Facebook)

At around 2:45 a.m. Saturday, Matthew Olson from Newport Beach was walking in traffic in the southbound 110 Freeway at 37th Street, according to California Highway Patrol, when he was hit by a Toyota C-HR.

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Then, while Olson was lying on the ground, he was struck by a second car, CHP reports.

The driver of the Toyota, 39-year-old Maxwell Weiner of Redondo Beach, stopped and attempted to render aid to Olson, but he died at the scene.

Weiner was later taken into custody on undisclosed charges.

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The driver of the second car did not stop after hitting Olson, CHP reports. That person remains at large. There was no description of the driver or their vehicle.

CHP investigators are still unsure what Olson was doing walking along the freeway.

Olson was set to be a freshman at USC, according to the Los Angeles Times, and attended Corona Del Mar High School, where he played basketball. On its Facebook page Saturday, the team posted a tribute to Olson in which it described him as an “incredible person, everything you can ask for in a student, Best Buddy, teammate, friend, brother, & son.”

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A little over two hours later, a woman walking along the northbound 110 Freeway in downtown Los Angeles was also struck and killed.