Heavy downpours that caused rivers to burst around Thailand have killed 57 people in nearly two weeks of flooding that officials are calling the worst in several decades, authorities said Wednesday. The fatalities have occurred in central, eastern and northeastern provinces and have affected more than 3 million people in 36 of Thailand's 76 provinces, government medical and disaster agencies said. The floods have eased in a third of those provinces. More than 4 million sandbags were used to erect walls this week in Bangkok along stretches of the Chao Praya River, which has swelled with runoffs from upper provinces that officials feared could inundate the capital.