Government supporters and opponents turned neighborhoods of Pakistan's largest city into battlegrounds Saturday, leaving at least 27 people dead in the worst political violence since President Gen. Pervez Musharraf suspended the chief justice.

The justice, Iftikhar Mohammed Chaudhry, flew to Karachi to attend a rally organized by his supporters but never made it out of the airport. He abandoned his plans in the face of street battles across the sprawling city.

Gunmen with assault rifles traded fire in a residential area of bungalows and concrete apartment blocks just a half-mile from the international airport, where nearby streets were blocked by shipping containers and immobilized trucks and gunfire left several activists lying in pools of their own blood. A private TV network came under attack as well, but stayed on the air as rioters torched vehicles outside.

Chaudhry took an evening flight back to the capital and it was unclear whether the rally at Karachi's high court would proceed.

The fighting broke out as Chaudhry arrived for what organizers hoped would be the largest in two months of rallies by lawyers and opposition parties calling for his reinstatement and for Musharraf to step down. Pro-government parties responded with their own show of strength.

Musharraf, speaking ahead of his own rally late Saturday in the capital, Islamabad, urged the nation to stand united and remain peaceful. He ruled out calling a state of emergency to contain the escalating unrest.

In Karachi, opposition activists accused a pro-government party, the Mutahida Qami Movement (MQM), of attacking them with batons and gunfire as they attempted to greet the judge at the airport.

An AP reporter saw MQM supporters calling for ammunition and firing from buildings, reportedly at opposition supporters, who fired back.

Doctors at the city's four main hospitals said 27 people were dead and more than 100 injured, many of them from gunshot wounds. The number of dead was confirmed by a senior security official in Karachi, who spoke on condition of anonymity because he is not authorized to speak publicly.

Men brandishing rifles and handguns marauded against a backdrop of burning cars and buses on the streets of the city, which has 15 million inhabitants and a history of political and ethnic violence.

In an afternoon speech by phone to a rally of thousands of his supporters in a Karachi square, MQM leader Altaf Hussain — who lives in exile in London — indirectly blamed Chaudhry for the violence, saying he should have heeded warnings from provincial officials to stay away.

Hussain urged the crowd to "control your emotions and demonstrate peace, as we are peace-loving people."

Musharraf, who took power in a bloodless coup in 1999 and is still army chief, was due to address a gathering in the capital, Islamabad, later Saturday that organizers forecast would draw over 300,000 ruling party supporters.

Critics accuse Musharraf of trying to sideline the independent-minded Chaudhry to head off legal challenges to his plan to seek a new five-year term later this year. The government maintains Chaudhry's March 9 ouster was not politically motivated and that he had abused his office.

Speaking earlier, Musharraf did not mention the Karachi violence, but ruled out declaring a state of emergency — which some analysts have suggested would let him keep power if his efforts to seek a new term while still army chief flounder.

"There is absolutely no requirement and absolutely no environment for taking such drastic measure," Musharraf was quoted as saying by the state-run Associated Press of Pakistan news agency.

But the government's failure to contain the unrest in Karachi, despite the presence of 15,000 security forces, will deepen the political turmoil gripping Pakistan.

In the 1990s, scores of MQM activists were arrested for allegedly kidnapping dozens of their rivals and attacking security forces. Party activists are still heavily armed, but critics say they enjoy impunity as part of Musharraf's government.