A 16-year-old boy died after the vehicle he was riding in, which had stalled on Interstate 580 in Pleasanton after an initial collision, was struck from behind at freeway speed by another vehicle whose driver didn't see the prior crash early Sunday morning, according to the California Highway Patrol.

The teenage passenger, whose name has not been released to date, sustained fatal injuries after the vehicle burst into flames immediately after the second collision, according to Officer Tyler Hahn of the CHP-Dublin office.

The call came into the CHP at about 2:35 a.m. Sunday about a three-vehicle collision on eastbound I-580 at the Hopyard Road interchange, Hahn said.

Subsequent investigation revealed there had actually been two separate crashes in quick succession. The initial two vehicles became disabled in the No. 2 and No. 4 lanes, respectively, after a non-injury crash, according to Hahn.

"The driver of a third vehicle failed to observe the vehicle blocking the two-lane and crashed into it at freeway speeds," Hahn said. "The previously disabled vehicle immediately became engulfed in flames, causing fatal injuries to a 16-year-old male passenger."

Hahn said the investigation thus far indicated that DUI was not a factor in the fatal collision. No other information was available about the identities or conditions of the other parties involved in the two crashes.

The CHP investigation remains ongoing, according to Hahn.

Officers had to close all lanes of eastbound I-580 in the area for about two hours for the investigation and cleanup, but the impact on traffic was minimal because vehicles were able to exit at Hopyard Road and re-enter the freeway where the closure was in place, the officer added.