Investigators haven’t yet determined the cause of a fire that destroyed a northeastern Iowa zoo and killed about one hundred animals. Gerald Slessor owns the River Ranch Campground Zoo near the Chickasaw County town of Nashua. He says he was gone for the weekend when he got a frantic call from his daughter telling him the barn was on fire.Slessor says his daughter, Jessica, and her boyfriend Tom Bucknell, tried to save the animals by breaking out windows, but the room was smoke-filled and the animals were all dead.Fire investigators have not issued a final report on the cause of the Saturday blaze, which Slessor says was fast-spreading.Exotic animals at the River Ranch included rabbits, chinchillas, hedgehogs, geckos, and bearded dragons from Australia. Also among the dead were Michelle and Monty, a pair of 200-pound Burmese pythons, and Lucy, a yellow foot tortoise from South America. Slessor says it was apparently the heat and smoke that killed the animals, not the flames.Animals that survived the fire include an antelope, camel, ostrich, and a wallaby because they were able to get outside. According to Slessor’s wife, Erica, the exotic animals were not insured and the building may have been underinsured because of all the improvements they had made.