CARPINTERIA, Calif. -

California Highway Patrol investigators are trying to understand why.  Trying to understand why a 16-year old Santa Barbara boy would drive the wrong way on the freeway, dying in a head-on crash with a semi truck.

16-year-old Daniel Perez died at the scene as his white mustang slammed into the big rig at 10:42 Wednesday evening, just south of Bates Road in Carpinteria.

Willie Lonie, Jr., 56, of Pearl, MS, was driving a Volvo 3XL semi truck, but was not injured in the crash. 

Perez's car rolled onto its roof, trapping him underneath.

The accident closed all northbound lanes and one southbound lane to clean up debris including an 20 gallons of fuel and oil. 

Northbound commuters were stuck in place until lanes re-opened around 5:45 a.m.  Because of the massive backup, traffic was significantly slowed all Thursday morning.

Perez was a junior at San Marcos High School, where grief counselors were called in to help friends and classmates deal with the sudden and tragic loss.