An early morning fire at a poultry processing plant in northeast China killed at least 93 people, officials said Monday. More than 300 workers were inside the plant in Jilin province when the fire broke out about 6 a.m., state-run Xinhua news agency said. About 100 of them were able to escape -- and told Xinhua that the gates to the plant were locked. Six hours later, firefighters were still battling to bring the blaze under control. A fire official told CNN that an explosion at the plant started the fire -- but the cause of the blast wasn't immediately known. "The complicated interior structure of the prefabricated house in which the fire broke out and the narrow exits have added difficulties to the rescue work, sources with rescue forces said," the Xinhua report said.