A gas-line explosion set part of a slum in Nairobi on fire Monday, killing at least 75 and injuring more than 100. Reporters saw piles of charred bodies and others floating in a nearby river of sewage. Wilfred Mbithi, a head Nairobi police officer, said some had jumped into the river trying to extinguish the flames. Many of the victims died rushing toward the fuel leak with buckets, trying to disperse it before an explosion. Homes in the slum are often built right up against the pipeline. At least 112 burn victims have arrived at the city’s national hospital, and officials said the death toll is certain to rise.