No one was injured in a fire and explosion that rocked an industrial area in Akron on Wednesday and prompted a large-scale evacuation. But a hazardous materials team didn’t reach the site for more than two hours because officials feared butadiene — the primary chemical used by Emerald Performance Materials — could cause a secondary explosion or chemical reaction with other materials there. Firefighters were forced to wait on the edge of the evacuation zone with residents and employees from nearby homes and businesses as officials scrambled to get a drone and airplane equipped with cameras over the factory to see what was burning and how hot. Finally, just after 3 p.m., hazardous materials teams suited up in full-body fire suits and breathing masks and ventured inside. By then, all that remained was a small fire burning on the factory’s roof. It was likely caused by towering flames that could be seen shooting skyward after the explosion.