Witnesses in southwestern Somalia say an explosion has killed four Ethiopian troops and triggered gunfire that killed two Somali civilians.

Residents of Baidoa said Tuesday that a roadside bomb killed the Ethiopian soldiers late Monday. The witnesses said other troops responded to the attack by opening fire, killing two civilian bystanders.

Baidoa is about 250 kilometers west of the capital, Mogadishu, and is the seat of the Somali parliament.

Ethiopian troops supporting Somalia's government come under frequent attack from Islamist insurgents. A joint government-Ethiopian offensive drove Islamists from power in southern Somalia in late 2006.

Separately, officials said 10 people were killed and at least 11 wounded in a land dispute Monday in the southwestern Gedo region.

Disputes between rival clans over land and water are common in Somalia, which has not had a stable central government since 1991.

Some information for this report was provided by AP .