Sinai is a small squatter community in Nairobi's industrial area, not far from Jomo Kenyatta International Airport. The oil pipeline, which slices across the community and apparently runs to the airport, sprung a huge leak, sending oil cascading down the community's streets and into the nearby Ngong River. Many community residents headed towards the leak, to gather some of the valuable fuel. Somehow, the oil ignited--the New York Times reports the blaze took hold because cinders from a nearby garbage fire blew over in the wind, though other sources speculate about different causes. But whatever happened, the blast of flame was deadly.
The Nation newspaper reports that a loose gasket in the pipeline was responsible for the oil leak, and notes that "There were two different accounts of the cause of the inferno. While some of the survivors said the petrol from the pipeline came with the fire, others said it was lit by a man smoking a cigarette." The paper also offers a 2 minute TV news report from the scene.
The Standard reports that oil pipelines have a lifespan of about 25 years, while this one had been in continual service for 33 years, adding that and a decade-old study commissioned by the public/private commission that manages the pipeline had concluded that it was obsolete--but that the commission rejected the report and instead expanded its usage. Just a few weeks back, the government's energy secretary called for it to be replaced within three years.
The Guardian also has details, and a short video.