Ethiopian troops allied to Somalia's shaky government opened fire on civilians in a street in southwestern Somalia, killing 13 on Wednesday after an explosion there killed two soldiers, witnesses said.

Witness Mohamud Ahmed Nur said an explosion apparently caused by a remote-controlled land mine killed the two Ethiopian troops, who were patrolling the town of Baidoa.

The soldiers, he said, then opened fire in all directions, killing at least 10 civilian passers-by outright.

Mohamed Hussein Diriye, a doctor at the town's main hospital, said three more people died later of their injuries and that seven others were still being treated at the hospital, he said.

"It was a horrific scene, blood scattered everywhere," said witness Jamal Haji. "I saw the dead bodies of at least 10 people lying in the middle of the road."

Faduma Tahlil said her 25-year-old son Abdi Muse was among those shot. "He was a peace-lover. ... why was he killed?" she wept.

"If the international community does not push the Ethiopians to stop such wicked acts, the remaining Somalis will die before their eyes."

Baidoa is 250 kilometers (155 miles) southwest of the capital, Mogadishu, and is the headquarters for the Somali parliament. Several senior government officials also live there.

Islamic insurgents, whom the Ethiopians drove out of the capital in 2006, are furious about the presence of those troops on their soil. They have stepped up attacks across the country in recent months, seizing towns and then voluntarily withdrawing, in a direct challenge to the government, which is struggling to exert its control.

The insurgents receive support from Ethiopia's archenemy Eritrea and have strong support among sections of the population.

Several international and local human rights groups have accused the Ethiopians of indiscriminately killing civilians.

"Our government is a puppet, the Ethiopians are doing whatever they want here ... and the government is passively watching," raged 62-year-old resident Qasim Molin Isgow after the Baidoa killings.

Somalia has been mired in violence since warlords overthrew dictator Mohamed Siad Barre in 1991 and then turned their heavily armed supporters on one another. The Horn of Africa nation is flooded with weapons and divided among warring clans.