What took place at Waco was pathetic and I didn't see the film, but I can't believe they pumped cyanide gas into the facility. If the FBI spokesman said that, I think he was mistaken.
CS Gas Used Against Davidians
The tear gas used by the FBI in the final assault against the Branch Davidians in Waco, Texas, was CS gas. All tear gases are considered nerve agents, which are banned for use in combat by international law, but are frequently used by governments to control large crowds. CS gas, which is very strong, is intended for use only in open-air environments, as it can be inflammable and harmful or lethal in closed environments like the Branch Davidians' home.
Death certificates for Branch Davidians who died in the April 19, 1993, fire indicate lethal levels of cyanide in the Davidian's blood, but none in their digestive systems, suggesting inhalation. The CS powder used to make CS gas is very high in cyanide content, according to the manufacturer.