Mogadishu, Somalia - A car bomb exploded in the heart of Somalia's capital on Monday, killing at least five people and wounding 20 others, police said. Al-Shabab claimed responsibility in a statement on its website.

Mostaf Abdi Abshir, a journalist with Radio Shabelle, told Al Jazeera the vehicle laden with explosives was detonated near a coffee shop opposite the immigration directorate.

"I heard a huge explosion on Maka al-Mukarama street and saw at least seven injured people," Abshir said.

Police officer Hussein Nor Mohamed told Al Jazeera that the death toll currently was five.

Major Aden Ibrahim, a police official, told Reuters news agency that the attack was carried out by a suicide bomber.

Abdikadir Abdirahman, the director of AMIN ambulances, said his organisation had removed eight bodies from the scene and taken more than two dozen wounded to hospital.

"The death toll may rise," he said.

Senior security officials were among the casualties, al-Shabab said.

"We are behind the blast," Sheikh Abdiasis Abu Musab, the group's military operations spokesman, told Reuters. "The targets were police, intelligence, military officials and immigration workers."

Al-Shabab was forced out of the capital and other major urban areas in Somalia by national and African Union multinational forces, but it continues to carry out deadly bombings and attacks in Mogadishu and elsewhere.

Targets have included hotels, military checkpoints and the presidential palace.

Earlier on Monday, three Somali soldiers on an ordnance-clearing mission were killed after a roadside bomb planted by the rebels exploded 90km north of the capital.

Somalia has been mired in conflict since 1991, when clan-based warlords overthrew dictator Siad Barre and then turned on each other.

Abdirisak Mohamud Tuuryare contributed to this report from Mogadishu