Hundreds of fighters who were battling Somalia's Islamic militia in the capital surrendered early Tuesday after a surge of violence that killed more than 70 people since Sunday, officials said.

The fighters, loyal to secular warlord Abdi Awale Qaybdiid, gave up their weapons and trucks to the Islamic militia, said Heyle Abdi, a top Islamic commander. The whereabouts of Qaybdiid were not immediately clear.

The Islamic fighters wrested Mogadishu from a U.S.-backed secular alliance of warlords last month, but Qaybdiid had refused to disarm.

• CountryWatch: Somalia

The new violence started Sunday and broke weeks of relative calm under the rule of the Islamic fighters, who have grown increasingly radical since seizing Mogadishu and establishing strict courts based on Islamic law.

"The war was inevitable because nobody can have authority in the city beyond the Islamic courts," Sheikh Sharif Sheikh Ahmed, a top Islamic official, said Monday.

Mortar shells and gunfire shook the city for two days, sending residents into homes and shops or fleeing Mogadishu altogether.

Somalia has been without an effective government since warlords overthrew its longtime dictator in 1991 and divided the nation into fiefdoms. The Islamic fundamentalists have stepped into the vacuum as an alternative military and political power.

The volatile nation in the Horn of Africa has been a particular concern to the United States, which has long-standing fears that Somalia will become a refuge for members of Usama bin Laden's terrorist network, much like Afghanistan did in the late 1990s.

U.S. officials cooperated with the warlords, hoping to capture three Al Qaeda leaders allegedly protected by the Islamic council who are accused in the deadly 1998 bombings at the U.S. embassies in Kenya and Tanzania.

But the Islamists prevailed, taking the U.S. by surprise and further marginalizing the country's interim government. The interim body was established with the help of the United Nations but is powerless outside its base in Baidoa, 150 kilometers (90 miles) from Mogadishu.