The death toll from floods and mudslides caused by heavy rains in Brazil's southern Rio Grande do Sul state jumped to 29, with another 60 people missing, according to the state's civil defense agency.Authorities in Rio Grande do Sul have declared a state of emergency as rescuers continue to search for dozens of people reported missing among the ruins of collapsed homes, bridges and roads.Storm damage has affected nearly 150 municipalities in the state, also injuring 36 people and displacing more than 10,000.Governor Eduardo Leite said Rio Grande do Sul was dealing with "the worst disaster in (its) history."As the rains continued, forecasts warned the states main Guaiba River, which has already overflowed its banks in some areas, would reach an extraordinary level of three meters.Entire communities in Rio Grande do Sul state have been completely cut off as persistent rains have destroyed bridges and blocked roads, and left towns without even telephone or internet services.The downpour started Monday and was expected to last through Friday. In some areas, such as valleys, mountain slopes and cities, more than 150 millimeters of rain fell in 24 hours, according to Brazil's National Institute of Meteorology.Weather across South America is affected by the climate phenomenon El Nio, a periodic naturally occurring event that warms surface waters in the Equatorial Pacific region. In March, heavy rains killed 25 people in southeast Brazil.