The crisis triggered by the ouster of Pakistan's top judge took an ominous and bloody ethnic turn Sunday, as the death toll from a weekend of street warfare rose to 41 and turned its volatile business capital into a city under siege.

Funeral processions were accompanied by more gunbattles and arson, ambulance crews were attacked and at least two people died in clashes between traditional rivals in Karachi — Pashtuns and Urdu-speakers linked to a party that backs President Gen. Pervez Musharraf.

The violence marked a serious escalation in a crisis that began with Musharraf ousting the head of the supreme court on March 9 and has hardened opposition to plans for the general, a key U.S. ally, to extend his nearly eight-year rule.

It also raised the specter of a return to ethnic bloodshed in a port city of 15 million people that serves as the hub of Pakistan's fast-growing economy and even raised fears for the nation's stability.

Rallies timed for a visit by suspended Chief Justice Iftikhar Mohammed Chaudhry on Saturday sparked gunfights and clashes between supporters and opponents of the government that left corpses in the streets.

Security forces failed to restore order Sunday, despite the deployment of armored personnel carriers and pickup trucks topped with machine guns to patrol the mostly deserted streets.

The fighting opened old wounds between Pashtuns and Urdu-speaking supporters of the pro-government Mutahida Qaumi Movement party. Opposition parties accused the MQM of initiating much of the violence, in which Pashtuns appeared to account for many of the dead.

Police officer Shad Masih said a Pashtun called Saifur Rehman was fatally shot by in an eastern district, and that three others were hospitalized with gunshot wounds. Masih said police dispersed a crowd in the area using tear gas.

To the west, police reported gunmen trading shots across a road dividing Banaras Colony, an ethnic Pashtun-dominated residential area, from a mainly Urdu-speaking quarter on the other side.

Muhammad Noorani, a 24-year-old Pashtun, was hit in the head by a bullet and was pronounced dead at the city's Abbasi Hospital, doctor Liaquat Nemon said.

Police said they found the bullet-ridden bodies of an MQM activist in one district and two men — apparently Pashtuns — in an MQM stronghold. Muzher Udin, another doctor at the Abbasi hospital, said the bodies of the two Pashtuns, tied up and blindfolded, were covered in wounds.

In a northern district, firefighters battled flames spreading through a row of Pashtun-owned shops after a funeral procession for an MQM activist killed the day before had passed.

Anwar Kazmi, an official for the Edhi charitable foundation said its ambulance crews had been shot at six times over the weekend. In one incident, unidentified gunmen shot dead a driver and two injured patients at a roadblock.

Based on reports from police and officials at four hospitals, the casualty toll rose to 41 dead and about 150 wounded.

On Saturday, officials said a security force of 15,000 was deployed in the city. But there was no sign that they had intervened to stop the violence, and opposition parties blamed Musharraf and the MQM for the violence.

"We condemn this mayhem and we believe that the MQM could not have done it without the active support of Gen. Pervez Musharraf," said Farhatullah Babar, a spokesman for the Pakistan People's Party of former Prime Minister Benazir Bhutto.

"It shows that the government wanted to create a situation of civil strife to find an excuse for imposing an emergency and postponing elections," Babar said.

In his own mass rally in Islamabad late Saturday, Musharraf insisted he would not declare an emergency, and said a presidential vote by lawmakers and parliamentary elections would go ahead as planned by year's end.

He urged opposition parties to stop protests in support of the judge.

"My heart was weeping when I saw that people were dying, they were being killed, they were being martyred," he told a crowd marshaled by the ruling Pakistan Muslim League party.

On Sunday, Minister of State for Information Tariq Azeem Khan said it was too early to say who was responsible for the "carnage." He said there was no "definite proof" of who was involved in the rioting and that the prime minister and the provincial government have ordered separate inquiries.

Farooq Sattar, a senior MQM lawmaker, accused opposition parties of "terrorism," claiming they had stirred violence in areas with mixed ethnic Pashtun and Punjabi populations.

"They tried to give an impression that the ethnic residents are fighting each other," Sattar said at a news conference in Karachi.

Shahi Syed, a Pashtun leader in Karachi and a senior member of the opposition Awami National Party, gave the government 72 hours to arrest those responsible for killing his associates, otherwise "we will take our own course."

The MQM is a coalition partner in both the government of Sindh province, of which Karachi is the capital, and the federal administration.

The Karachi-based party draws its main support from Mohajirs — Muslims who fled India at partition and independence from Britain in 1947 and their descendants — and has a reputation for militancy. Musharraf himself is a Mohajir but is not in the MQM.

The party emerged in the 1980s when Mohajir resentment of Pashtun control of businesses such as public transport boiled over into violence that killed hundreds. In the 1990s, MQM activists battled security forces during clampdowns against violent organized crime.

The crackdowns were ordered by governments headed by the parties now spearheading the opposition to Musharraf.

Sindh Home Secretary Ghulam Muhammad Mohtarem said Sunday that 3,000 extra paramilitary rangers were being called into the city and that security forces were authorized to shoot to counter any "major breakdown of law and order."

Mohtarem said authorities had banned all political rallies and declared a day of mourning for Monday, when some opposition leaders have called for a national strike.

Rasul Baksh Rais, professor of political science at Lahore University of Management Sciences, said the perception that authorities used the MQM to "teach a lesson" to its opponents could backfire on Musharraf.

Ethnic violence could flare in other regions, such as the already unstable Pashtun belt along the Afghan border, Rais said.

"If the government resorts to violence, what can you expect from the opposition because then there is no faith in the law-enforcing agencies and there is no faith in the credibility of the government and whatever it says," he said.

Talat Masood, a prominent political analyst and retired army general, said the crisis had polarized Pakistani politics to an extent "bordering on civil war."

"I think it has weakened the state structure and its extremely detrimental to the image of Pakistan and the answer lies in having elections as soon as possible to defuse the situation," Masood said.