A car bomb has exploded outside the port of the Somali capital Mogadishu, killing several people and injuring many others. Officials say the death toll is likely to increase. A bomb exploded at the entrance of Mogadishu port on Sunday, killing at least 12 civilians and injuring dozens of others. "The death toll may rise. There were porters and public vehicles queuing outside the gate when the blast occurred," police officer Abdikadi Ahmed told journalists. An ambulance service official speaking to the Agence France-Presse news agency reported a higher death toll and said nearly 50 people had been injured. The blast took place when a man drove a van packed with explosives into a police station and a security checkpoint at the entrance. The explosion severely damaged the building and thick plumes of black smoke could be seen throughout the city. The Islamic extremist group al-Shabab took responsibility for the attack through an official statement on its radio channel, Radio Andalus. The al-Shabab insurgency aims to drive out African Union peacekeepers, topple the Somalian government and create a state based on orthodox Islam.