Armed Somali group al-Shabab has claimed responsibility for the attack and ongoing siege of an upscale shopping mall in the Kenyan capital of Nairobi that has left at least 30 people dead and 50 injured.Kenyan security forces have arrested one of the gunmen who attacked the mall on Saturday, the Kenyan presidency said on Twitter.The east African country's head of police, David Kimaiyo, said via Twitter that several other assailants had been pinned down after soldiers and police moved into the mall to hunt down the attackers.Al Jazeera's Caroline Malone reports.
