Heavy fighting resumed in Somalia's capital despite a brief lull following a ceasefire, with almost 100 dead and hundreds more wounded in the clashes.
The fighters rejected attempts by traditional elders to stop the battles
An alliance of warlords and an Islamist militia have fought each other over the past four days in northern districts.
Islamic militia leader Sheikh Sharif Ahmed called a unilateral truce on Tuesday in response to appeals from those affected by the violence.
But his opponents said the truce was called because of a lack of ammunition.
The United Nations has appealed to both sides to halt the clashes.
"The indiscriminate use of heavy machine guns, mortars, rocket-propelled grenades and artillery in and between urban areas is unacceptable," said chief UN envoy to Somalia Francois Lonseny Fall.
The BBC's Mohammed Olad Hassan in Mogadishu says as night fell on Wednesday, battles in the city died down.
A mother and her three-year-old child were amongst those killed in the crossfire in the north and throughout the day hundreds of civilians continued to flee, he said.
The warlords' alliance spokesman Hussein Gutale Rageh said they would only accept the ceasefire if their rivals withdrew from territory they have occupied during the fighting.
Prime Minister Ali Mohamed Ghedi, who is based in Baidoa, has also called on the two sides to stop the fighting.
This is the second round of the city's most serious fighting in a decade. In March, clashes between the two sides killed at least 90 people.
Late on Tuesday, Mr Shariff Ahmed, the chairman of the Joint Islamic Courts in Mogadishu, said his militias' ceasefire was unconditional, but added a warning.
Many of the casualties are civilians caught in the crossfire
"But if we are attacked and somebody fires guns at us, we will not sit and wait," he said.
Our correspondent says civil society groups are meeting the warlords to get them to accept the ceasefire.
During the day, traditional elders could be seen waving white flags at both sides trying to get them to cease their fire, but to no avail, he says.
The fighting started late on Sunday, when an alliance of warlords attacked the vehicle of a group allied to the Islamic courts, according to eyewitnesses.
The battles have been fierce, with hundreds of people wounded.
"How can we trust unilateral cease fire, while we can see with our eyes ongoing militia mobilisations by both sides?" Ahmed Mo'alin, a school teacher, whose house was destroyed by a mortar round in the battle, told the BBC.
Hundreds of people have fled the CC district of north Mogadishu, where the fighting broke out.
Khaliif Jumale, 37, loaded his wife and three children onto a donkey cart early on Monday and said he was taking them to Afgoye, 30km (29 miles) north of Mogadishu.
"There is no reliable place here when it comes to our security," he said.
"Every corner of the city, the militias of the same rival groups have taken up positions to prepare for more lethal fighting... there is no cold place in an inferno."
The Islamic courts have restored order to some parts of the city by providing justice under Sharia - Islamic law.
The alliance of warlords recently created the Alliance for the Restoration of Peace and Counter-Terrorism.
It accuses the Islamic courts of sheltering foreign al-Qaeda leaders, while the courts say the alliance is a pawn of the United States.
Last week, Somali President Abdullahi Yusuf accused the US of funding the coalition of warlords.
The US government says it does support efforts to restore stability to Somalia but refuses to give details on who it backs and how, the BBC's East Africa correspondent Adam Mynott says.
It has an anti-terror task force based in nearby Djibouti.
Somalia has not had an effective national authority for 15 years after the ousting of President Siad Barre in 1991.