Two Algerian Air Force planes collided Monday evening while on a night mission in the western border area, killing all four pilots who were on board. Security sources have reported that the incident took place between the villages Hassi Zehana and Sidi Abdelli in the border province of Tlemcen. The Ministry for National Defence released a statement immediately naming the aeroplanes involved in the collision as well as the four Border Guard pilots. An investigation into the incident will be launched, the statement said. Local sources said the two aeroplanes had taken off from the Tafraoui irbase in the province of Oran and were on a training mission. The two aeroplanes, the sources said, collided late on Monday due to the heavy fog that enveloped the area. The collision triggered panic among the residents of Hassi Zehana and Sidi Abdelli along the Algerian-Moroccan borders. Algerian television channel al-Nahar broadcast a piece of footage shot by local citizens showing flames rising from the collision.