Witnesses in Somalia's capital say at least eight people have been killed in a land mine explosion.

The blast occurred late Saturday in Mogadishu's Waberi district, near a police station.  Witnesses say five members of the security forces were killed, along with at least three civilians.

No one has claimed responsibility for the attack, though friends and relatives of the dead blamed the insurgent group al-Shabab.

Somalia's transitional government is battling Islamist groups who are trying to impose a harsh form of sharia, or Islamic law, on the country.

Earlier on Saturday, the militants fired mortar rounds at the Mogadishu airport, prompting return fire from government troops and African Union peacekeepers.

Reports from the city say at least 10 people were killed, most of them civilians.

The airport is one of the few areas of Mogadishu the government controls.  Al-Shabab and another Islamist group, Hizbul Islam, control most of the capital and large parts of southern and central Somalia.

The U.N.-backed government has promised a major offensive against the Islamists for months, but the offensive has yet to materialize.

Somalia has not had a stable central government since 1991.

Some information for this report provided by AP, AFP and Reuters.