A pall of smoke hangs over the Westgate shopping mall in Nairobi on Wednesday. Kenya's president has declared three days of mourning for those killed in the siege that began at the weekend. At least 67 people lost their lives when gunmen stormed the shopping centre in the Kenyan capital. The exact number of dead is far from clear. Three floors of the building collapsed as the drama neared its end. An unknown number of bodies are lying under the wreckage of steel and concrete.