Blast rocks Kenyan capital

Dense smoke billows from a badly damaged building after an explosion at a shopping centre in downtown Nairobi.<br/> <br />Sirens blare as emergency personnel reach the bloody scene.<br/> <br />At least 15 people were reported wounded, 11 of them critically.<br/> <br />Nairobi's Police Commissioner said blackened wires inside the centre indicate a possible electrical fault, but did not rule out a bombing.<br/> <br />One witness said the blast knocked him down.<br/> <br />(SOUNDBITE) (Kiswahili) EYEWITNESS WHO DECLINED TO GIVE NAME, SAYING:<br/> <br />"I was passing by when I heard a loud blast and it knocked me down, I saw a vehicle that was nearby thrown to one side. I just took off running"<br/> <br />There have been a string of deadly attacks in Nairobi and the port city of Mombassa since Kenya sent troops into Somalia in October to fight al Qaeda-linked militants.<br/> <br />Nairobi has blamed the al Shabaab militants, who merged with al Qaeda earlier this year, for the surge in violence.<br/> <br />Sarah Sheffer, Reuters