OMAHA, Neb. — Firefighters in eastern Nebraska battled a fire for hours following an explosion Tuesday at a wood pellet manufacturing plant, but authorities said they have been unable to get close enough to search for three people believed to be missing. The explosion happened at the Horizon Biofuels plant, which makes animal bedding and wood pellets for heating and smoking food, on the south end of Fremont, Nebraska. Fremont Mayor Joey Spellerberg said three individuals were in the building, but “that’s all we can say at this point,” he said in a briefing Tuesday afternoon. …The facility uses tons of wood waste to manufacture their wood fuel pellets.