A third person has died in flooding caused by the rupture of a red sludge reservoir at an alumina plant in western Hungary, rescue services said Tuesday. Six people were missing and 120 injured in what officials said was an ecological disaster.The sludge, a waste product in aluminum production, contains heavy metals and is toxic if ingested. Many of the injured sustained burns as the sludge seeped through their clothes. Two of the injured were in life threatening condition. An elderly woman, a young man and a 3-year-old child were killed in the flooding.The chemical burns caused by the sludge could take days to reveal themselves and what may seem like superficial injuries could later cause damage to deeper tissue, Peter Jakabos, a doctor on duty at a hospital in Gyor where several of the injured were taken, said on state television.The government declared a state of emergency in three counties affected by the flooding. Several hundred tons of plaster were being poured into the Marcal river to bind the toxic sludge and prevent it from flowing on, the National Disaster Management Directorate said.