ONTARIO, Calif. - At least two people were killed when a "large amount" of fireworks caused an explosion in an Ontario neighborhood on Tuesday afternoon.Both fatalities were "in the area of the explosion," fire officials said during an afternoon press conference, but authorities have not yet determined the identities or genders of those deceased.Fire crews were having to battle the flames from a distance because they're not sure if there is more explosive material at the scene.An evacuation order was issued for residents in the 300 and 400 block W.