July 3 (UPI) -- Seven people remain unaccounted for following Tuesday's explosion of a northern California fireworks warehouse, officials said. The warehouse located near Esparto, about 36 miles northwest of Sacramento, exploded at about 5:50 p.m. PDT Tuesday following a fire erupting on the compound. The cause of the fire remains under investigation. The Esparto Fire Protection District and Cal Fire said in an update Wednesday that first responders and investigators are working with the