Thousands of people have fled their homes, and at least 13 people have been killed and dozens injured, as rival militias clashed in Somalia's capital, Mogadishu, residents told IRIN on Thursday.
Medical sources added that at least 20 people have been wounded and taken to hospitals within the city which was abandoned by the Union of Islamic Courts (UIC) militia on Wednesday.
The fighting began in the morning in the Yaqshiid district of north Mogadishu, after militia tried to loot an arms storage warehouse, reported Hassan Mahamud Ahmed, editor of the San'aa newspaper in Mogadishu.
Ahmed said the fighting in Mogadishu was sparked by the breakdown of law and order after the UIC left the city.
"Each clan is now trying to rearm and repossess weapons taken from them by the courts, in anticipation of the return of the warlords," he said.
He added that there are also fears that the fighting might intensify if the interim government (TFG), backed by Ethiopian forces, tried to take Mogadishu by force. Some of the TFG and their Ethiopian backers are reported to be on the outskirts of Mogadishu.
Government spokesman, Abdirahman Dinari, told IRIN on Thursday that "the government did not wish to take the city by force", and that the city would not slide into lawlessness.
"We have been in constant contact with elders and civil society groups to make sure that there is a smooth and peaceful handover, and we expect that to happen soon. It was few militias who are trying to take advantage of the situation and they will be dealt with," he said.
Meanwhile, many UIC fighters and their leaders were reported to be heading south, "possibly to Kismayo", an unnamed local resident said. He added that their departure had created a vacuum in the city "and it is being filled by freelance militias".
He said clan militias had taken to the streets with "technicals" - pick-ups mounted with heavy weapons - "and have already taken over the airport and port".
The UIC has dominated Mogadishu after capturing the city in June. The Islamic Courts reopened the port and airport there in August, after they had been closed for more than 11 years.
The UIC's influence stretches throughout much of southern Somalia. But after nine days of fighting, the TFG forces, backed by Ethiopian forces with heavy weapons and aircraft, have pushed the UIC from most of the territory it controlled.
Most businesses in the city had closed on Thursday, with traders "waiting to see how things develop", the resident said.
Ali Imaan Sharmarke, the managing partner for HornAfrik, radio and television, told IRIN that "for the first time, since July, I am driving with guards".
He said that the city was "on the brink of going back to the situation in the 1990s, when freelance militias roamed the streets".
"The civil society, along with elders, is trying to contain the situation, before it gets out of hand," Abdullahi Shirwa of the Civil Society in Action, a coalition of civil-society groups, said. "The last thing we want is return to the old ways."