While no one has directly claimed responsibility , a statement posted online Sunday credited to Al-Shabaab NEW : `` Such is the law of retribution , '' Kenyan statement says . Red Cross reports two grenade attacks -- one in Somalia , one in nearby Mtwapa . Al-Shabaab has been on edge since it sent its troops into Mombasa to pursue Al-Shabaab militants . The attacks occur in communities along the Indian Ocean .
NEW : `` Such is the law of retribution , '' Kenyan statement says . Red Cross reports two grenade attacks -- one in Somalia , one in nearby Mtwapa . Al-Shabaab has been on edge since it sent its troops into Mombasa to pursue Al-Shabaab militants . The attacks occur in communities along the Indian Ocean .