Mortar fire killed three people and wounded six in the Somali capital Wednesday after a night of street fighting left at least 11 people dead and dozens injured, witnesses and health officials said.

Fadumo Muyadin, a schoolteacher, told The Associated Press that she saw two women and one man dead when she went to see whether victims of the attack in the northern part of Mogadishu needed help. She said she drove some of the wounded to a hospital.

It was not clear who fired the mortars, witnesses said.

The fighting late Tuesday in northern and southern neighborhoods between Ethiopian troops backing Somalia's fragile interim government and insurgents could be heard for miles. It was unclear what started the shooting.

"Tuesday night's fighting exceeded in its intensity the recent fighting in Mogadishu," said Mohamed Jumale, a resident of the southern neighborhood of Ali Kamin.

"I saw three bodies of the same family lying in a partly destroyed home after a missile crashed into their home," said Hassan Abdi Saleh. "Three others sustained light injuries."

Firing from the hilltop presidential palace, Ethiopian tanks fired dozens of cannon rounds at insurgent positions in the southern Tawfiq district, said Hussein Farah Siyad, an elder of the capital's dominant clan, the Hawiye. Some of the shells hit in northern and western areas, he said.

Abdiyo Mohamud Siyad, who lives in Tawfiq, said several shells hit her neighborhood, killing four people and injuring five others.

An Associated Press cameraman saw the bodies of four other civilians in a house destroyed by a mortar shell.

Dahir Dhere, director of Medina hospital, said 21 people wounded in the overnight fighting, including an 11-year-old girl, were brought to the hospital.

The Somali Red Crescent Society reported that 12 injured civilians were taken to Keysaney Hospital, which the group helps manage.

Somali troops backed by Ethiopian forces ousted the country's Islamic movement from Mogadishu and other strongholds in December. Remnants of the Islamic group have vowed to wage an Iraq-style insurgency and the capital has seen of waves of violence. The most deadly raged in late March and saw hundreds of people killed, most of them civilians.

Diplomats have said, though, that the violence also involves clan militias that are not necessarily linked to the Islamic extremists.

Somalia has not had an effective national government since 1991, when warlords overthrew dictator Mohamed Siad Barre and then turned on one another, throwing the country into anarchy.

The transitional government was formed in 2004 with U.N. help, but has struggled to exert control.