At least 52 people were killed and 120 were wounded in heavy fighting Saturday in the Somali capital, a human rights group and hospital officials said.

Fighting between Islamic insurgents and Ethiopian troops backing the government had stopped overnight, but both sides were again battling by Saturday morning. Hundreds of people fled the violence on foot and piling into trucks, and hospitals were overwhelmed with casualties.

Somalia's Elman Human Rights Organization said Mogadishu residents, hospital workers and human rights workers told it that at least 52 civilians had been killed and many wounded Saturday.

Several hospital sources told The Associated Press they had received at least 120 wounded from Saturday's fighting. They spoke on condition of anonymity for security reasons.

The new tallies bring the death toll in four days of fighting in Mogadishu to at least 165 people and more than 229 wounded, according to the human rights group.

Saturday's violence is the worst in recent years, said Sudan Ali Ahmed, the chairman of the decade-old Elman Human Rights Organization.

"I call on the both sides to stop the fighting and shelling without any condition," to save civilian lives, Ahmed told the AP by telephone.

The U.N. refugee agency says that 321,000 people have fled Mogadishu since February because of the violence.

An AP reporter could hear from his house the boom of mortar shells that Ethiopian troops fired from the nearby presidential palace in the direction of northern Mogadishu, which seems to be the main battlefield between the two sides.

Local radio stations reported that the insurgents and Ethiopians engaged in street battles mainly in the capital's southern and northern districts.

One station, HornAfrik, was hit by a mortar and went off the air. A reporter and a technician were injured, said Abdullahi Kulmiye, a colleague of theirs.

Hundreds of women, children and men walked or got onto trucks to flee to safer parts of Mogadishu, such as its northern outskirts, or to leave the city altogether for southern or central towns.