Nairobi - Several people were wounded in a large blast in the centre of the Kenyan capital Nairobi on Monday, although the cause of the explosion was not known, an AFP reporter at the scene said.
Kenya has been hit by a wave of grenade attacks the police have repeatedly blamed on Somalia's al-Qaeda linked Shabaab insurgents or its supporters.
Last month the hardline Shabaab warned Kenya of revenge attacks for sending tanks and troops into Somalia in October.
Minutes after the blast the pro-Shabaab Twitter site Al-Kataib reported a "huge explosion in Nairobi" although did not specifically claim any responsibility.
Police sources said that at least six people were wounded, and that they were investigating whether the blast was a bomb or an accident.
The wounded were carried from the explosion in a commercial building, as emergency services raced to the scene and tried to rope off the area, as thousands of people ran towards the blast site.
The Kenyan Red Cross said a disaster response team had been sent to the blast on the central Moi Avenue in the commercial heart of Nairobi.