Heavy fighting in the Somali capital killed at least 52 people and left 120 wounded in a single day, a human rights group and hospital officials said. Islamic insurgents, who are based in residential areas, battled Ethiopian troops in the southern and northern districts of Mogadishu. Hundreds of people fled the violence on foot or piled into trucks, and hospitals were overwhelmed with casualties. Many of the Islamic insurgents are masked and fire shoulder-held rocket launchers or Kalashnikov assault rifles. They also use pickups mounted with machine-guns. Ethiopian soldiers, who are in Mogadishu to back Somalia's fragile government, normally fight from public spaces such as street junctions or government buildings, firing long-range mortars. They also use tanks and machine guns. An Associated Press cameraman saw 11 bodies on the streets as he passed through Mogadishu's southern districts to get to the main airport. Some of the bodies were missing legs or heads. At one point during the journey, a mortar hit the vehicle in front of his, but everyone survived the blast. 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 an unknown number 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, with 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 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 UN 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. One radio station, HornAfrik, was hit by a mortar and went off the air. A reporter and a technician were injured, said Abdullahi Kulmiye, a colleague. Residents fled their single-story homes to seek shelter on the ground floors of taller buildings, believing that the higher roofs would take the brunt of damage from mortar shells that pounded their neighborhoods, said Aden Mohamed, a former banker who had sought refuge in such a home. Others had little to shelter themselves with. An Associated Press cameraman saw a man hiding from the shells under a tree. 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. Those traveling on foot carried on their heads cooking utensils, bedding and clothes wrapped in sheets. Some looked weak and said they had not eaten for days. "I prefer to flee my home to a safe place to avoid the shelling," said a mother of eight who only gave her name as Faduma. She said she had not eaten for two days and that during March battles between the insurgents and Ethiopians, her husband and eldest daughter were killed. "It is better to die in a safe place hungry and thirsty than to wait for mortar shells," said Faduma, whose home is in the northern Mogadishu area of Kungal, a known insurgent base and the scene of some of the heaviest fighting in recent days. In Kungal, Ethiopian soldiers and insurgent combatants fight within sight of each other. The US Ambassador to Kenya and Somalia, Michael Ranneberger, said the violence in Mogadishu has not been organized and was carried out by clan rivals and remnants of an ousted Islamic movement that has threatened an Iraq-style insurgency. "They are trying to create an insurgency," Ranneberger told the AP from Kenya. "But at this point it's opportunistic violence. They're not organized like an insurgency." Somali troops backed by Ethiopian forces ousted the Council of Islamic Courts from Mogadishu and other strongholds in December. Since then the capital has seen of waves of violence. The most deadly began in late March and saw hundreds of people killed, most of them civilians. Ranneberger said he believes the situation will calm down because of the transitional government's efforts to organize a credible national reconciliation conference. The conference has been postponed twice due to the violence in Mogadishu. It is now scheduled for mid-June. 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 UN help, but has struggled to extend its control over the country.