a car plunged off a road into los angeles harbor on thursday , and two children pulled from the submerged vehicle were hospitalized .
the adults were described as being in fair condition but ` clearly emotionally distraught '
witnesses said the car appeared to speed up as it neared the edge .
firefighter miguel meza who dove into the water in san pedro after a car carrying a family of four plunged into the water has been hailed a hero .