Kenya capital hit by large explosion Police say the Nairobi explosion, wounding at least 16, has no obvious cause. A previous blast in Mombasa, Kenya, on 15 May was blamed on the Somali militant group al-Shabaab. Photograph: Str/AP An explosion ripped through a building full of small shops in downtown Nairobi on Monday, wounding at least 16 people, the police commissioner said. He could not immediately confirm what caused the blast. The force of the explosion ripped apart the one-story building's aluminum roof, but a high-rise building with a glass exterior right next to the blast did not appear to sustain major damage. Police commissioner Mathew Iteere said at least 16 people were wounded. Another high-ranking police official said there were no obvious signs that the blast was caused by a terrorist's bomb. No ball bearings or nails lethal shrapnel packed into bombs were found, and officials were investigating the possibility that a faulty electrical line caused the explosion. The official said he could not be quoted by name. Let me not speculate this is a terrorist attack. It could be a wire fault," said Orwa Ojode, assistance minister for internal security. People with bloody wounds received medical care right after the blast, as authorities tried to usher hundreds of people in the street away from the scene. TV images showed thick black smoke billowing out of the building just after the blast. The smoke then turned white. Al-Shabaab militants from neighbouring Somalia have long threatened to carry out substantial attacks in Kenya after Nairobi's decision last October to send troops into Somalia to take on the militants. Kenya has suffered a series of grenade attacks in recent months, but Monday's blast appeared to have been caused by something larger.