US Air Force heavy transport aircraft, including C-5 and C-17 cargo planes, are seen parked at Osan Air Base in Pyeongtaek, Gyeonggi Province. (Yonhap) A white phosphorus leak occurred at Osan Air Base, a US military installation in Pyeongtaek, Gyeonggi Province, on Tuesday, prompting authorities to advise nearby residents to evacuate.According to fire and police officials, the leak was reported at around 4:54 p.m. at Osan Air Base, also known as K-55, in Seotan-myeon, Pyeongtaek.White phosphorus produces thick white smoke when exposed to oxygen and is used by the military to create smoke screens. The substance is highly reactive and can ignite spontaneously in the air. Contact with the skin can cause severe burns, while inhaling large amounts of its fumes can be fatal.Firefighters were dispatched after receiving a report of a suspected chemical leak from a munition.Authorities deployed nine vehicles and 31 personnel to cordon off the area and enforce safety measures.Shortly after the incident, the Pyeongtaek city government sent an emergency alert advising nearby residents to move to a safe location and avoid skin exposure.Fire, police and military authorities plan to investigate the exact cause of the leak once the area is deemed safe.