Updated

A fundamentalist Islamic force poured dozens of troops into the battle for a strategic road in Somalia's capital on Thursday in a clash with secular warlords that has left at least 130 dead — most passers-by caught in the crossfire — over the past five days.

The heavily armed reinforcements arrived in pickup trucks mounted with heavy machine guns. Fighters from both sides closed in on each other following a night of artillery exchanges that sent thousands of civilians fleeing the Sii-Sii neighborhood of northern Mogadishu.

Mogadishu residents described it as the worst fighting in more than a decade of lawlessness. Thousands of families were fleeing the capital.

While tending to his wife in the hospital, Mohamud Jama said his three children were killed when three mortar rounds struck his house.

"This is the first time we have witnessed people fighting in Somalia and targeting civilians in such a savage way," Jama said.

Militia loyal to the Islamic Court Union have been fighting since Sunday to capture a strategic road through northern Mogadishu from the Alliance for the Restoration of Peace and Counterterrorism. While the alliance has held the road through Sii-Sii, the courts have controlled the neighborhoods on either side.

The alliance accuses the union of having ties to Al Qaeda, while the Islamic group say the warlords are puppets of the United States. The courts are popular in Mogadishu because in recent years they have provided the only form of governance in the city, though in the past they have always been divided along clan lines. They are also considered to be fighting for Somalia, not an outside force.

Islamic fundamentalists have portrayed themselves as an alternative capable of bringing order and peace to a country that has had no effective central government since 1991, but they have not hesitated to use force. They have come to the fore just as a U.N.-backed transitional government has tried to assert control from Baidoa, 150 miles west of Mogadishu, because the capital is considered unsafe. Some of the warlords behind the alliance are members of the transitional parliament, though they are fighting the Islamic group on their own.

Both sides have been squaring off for a major battle for control of the city in recent weeks. Islamic radicals have built up their forces as part of a campaign to install an Islamic government in Somalia, something opposed by warlords who divided the country into clan-based fiefdoms following the overthrow of longtime dictator Mohamed Siad Barre in 1991.

This latest fighting may only be the beginning. Other clan militias with loose loyalties to both sides have not joined in the fighting yet, but they continue to man defenses in the neighborhoods they control and tensions are rising.

Medical officials reported that 34 people died in the fighting since nightfall Wednesday. More than 250 people have been wounded in the fighting since Wednesday, doctors have said.

"The fighting continues killing our brothers and sisters in front of us, so we decided to leave the city rather than watching them in a pool of blood," said Khasim Siidow, a father of eight children, who was on minibus to Wanlaweyn, 55 miles south west of Mogadishu.

Twelve shells missed their target overnight, landing on civilian homes far from the fighting, witnesses said.

"In one event, seven people of the same family — including three children — died when a mortar hit their house in Huriwaa district," Dayah Idiris, the victims' neighbor, told The Associated Press.

The Italian missionary news agency MISNA spoke by telephone with a missionary nun, Sister Maria Bernarda Roncacci, who works in a children's hospital and orphanage in Mogadishu.

"We are a few kilometers from the area of the clashes, but we can clearly hear explosions and heavy arms fire," she was quoted as saying. "They told us that last night as well hundreds of persons fled the neighborhood where the fighting is."

Islamic Court Union chairman Sheik Sharif Sheik Ahmed has promised every night to observe a cease-fire, but so far none has taken hold. Nuur Daqle, one of the alliance's commanders, said he was ready to observe a cease-fire, but that the Islamic fighters continue shooting at his men.

The International Committee of the Red Cross said it was extremely concerned about "the consequences in humanitarian terms of the intense armed clashes currently under way in Mogadishu."

Rumors abound that the United States is backing the alliance. Transitional President Abdullahi Yusuf Ahmed told the Associated Press in an interview last week that he believes Washington is supporting the militia as a way of fighting several senior Al Qaeda operatives that are being protected by radical clerics. The U.S. has said only that it had met with a wide variety of Somali leaders in an effort to fight international terrorists in the country.

At the United Nations Wednesday, the Security Council urged all nations to adhere to an existing arms embargo in Somalia. But the council ignored recommendations from one of its own committees that travel bans and asset freezes be imposed against some Somali warlords.