MOGADISHU (Reuters) - A huge explosion rocked Somalia's capital Mogadishu early on Thursday, triggering a plume of smoke which rose from the blast site amid gunfire, according to a Reuters witness.

       There was no immediate claim of responsibility but Islamist group al Shabaab frequently carries out bombings in the Horn of Africa country.

       (Reporting by Abdi Sheikh; Writing by Elias Biryabarema; Editing by Muralikumar Anantharaman)