Mohamed Abdel Razik El-Rizka, an international expert in weapons of mass destruction, said the gas used by security forces against demonstrators in Cairo's Tahrir Square and on Mohamed Mahmoud Street was not nerve gas. Rizka said it was most likely teargas, adding that nerve gases is only used in war and is fired at far-away targets, He said that scientifically, nerve gases can not be used in grenades to disperse people. He said nerve gas is lethal, spreads rapidly, and leads to immediate death. “The gas used to disperse the demonstrators on Mohamed Mahmoud Street can not be nerve gases because if it was, all the demonstrators and the security forces would have died,” he said.