Oncoming traffic attempted to dodge Heitmann, but he collided with a 2010 Kia minivan occupied by 43-year-old Aileen Pizarro and her 12-year-old daughter Aryana.
Trevor Heitmann, 18, drove his high speed $500,000 McLaren the wrong way down a freeway at 100 m.p.h.
Heitmann, 18, was driving a high-end 2014 McLaren sports vehicle the wrong way on Interstate 805 when he hit a Hyundai SUV Thursday afternoon, reports KSWB.
"At the time of the crash, he could have been going over 100 miles per hour", CHP Officer Jake Sanchez told the newspaper.
The second incident happened about a half-hour before the crash on 805.
Heitmann is popular on YouTube, and has close to 900,000 subscribers on his channel.
Heitmann was known by online gaming fans as "McSkillet", who watched him play the first-person shooter "Counter-Strike: Global Offensive" on video streaming sites such as YouTube.
Heitmann last posted five months ago, but in a video in December he showed off his expensive McLaren, according to BuzzFeed News.
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Witnesses told police the 18-year-old was driving the wrong way down a busy highway at 160km/h when his McLaren sports auto hit another vehicle.
There were several other cars involved in the crash.
The fatal vehicle accident took place 30 minutes after Heitmann crashed his sports auto into a gate at Ashley Falls Elementary School, San Diego Police said.
Heitmann, who was also heavily involved in the CounterStrike gambling scene, made headlines in 2016 after he posted an April Fool's joke video that led to major swings on the game's marketplace.
The sports auto was also involved in an earlier incident where it drove into the fence of an elementary school but no one was injured.