Kenyan police have linked the Al-Shabaab militant group to the Nairobi grenade attack that killed at least five people and wounded nearly 60 others on Saturday night."This is a cowardly act by Al-Shabaab elements," police spokesman Charles Owino told reporters at the Machakos country bus station, the site of the attack."But we will not relent in the war. We will get them and we will continue with the war."Kenyan troops are currently fighting Al-Shabaab in neighbouring Somalia.A spokesman at the city's main hospital, Kenyatta National Hospital, said at least seven other people were in a critical condition following the attack, in which witnesses reported seeing grenades thrown from a moving vehicle.Vice President Kalonzo Musyoka, while visiting survivors at the hospital, called for calm and reiterated that the Al-Shaabab militia would be dealt with.