At least five people were killed and eight injured in a crash involving multiple vehicles in the metro area Thursday, authorities said.

A pregnant woman was among the three adult victims, and her fetus did not survive, California Highway Patrol said.

A 3-year-old was also killed, according to a law enforcement source familiar with the investigation.

At a Thursday evening news conference, California Highway Patrol, said the remains of another victim were found in the wreckage.

Two adults and six minors were taken to area hospitals after the crash, Highway Patrol spokesman Franco Pepi said.

At least six vehicles were involved, and three were in flames when Highway Patrol arrived

It was not clear how many of the vehicles were part of the initial collision.

The agency is investigating the cause of the crash and said speed is a contributing factor.