Supporters and opponents of President Gen. Pervez Musharraf turned Pakistan's largest city into a battleground Saturday, trading gunfire that left 27 people dead and wrecked plans for a major opposition rally. The violence was the worst to emerge from a political crisis shaking the military-dominated government under Musharraf, a vital US ally who provoked the turmoil by ousting the head of the Supreme Court. Chief Justice Iftikhar Mohammed Chaudhry flew to Karachi on Saturday for what organizers had billed as the largest in two months of rallies by lawyers and opposition parties calling for his reinstatement and for Musharraf to step down. But a pro-government party responded with its own show of strength, prompting battles and rioting, and the judge never made it beyond the airport, where nearby streets were blocked by shipping containers and immobilized trucks, and gunfire left several activists lying in pools of their own blood. Chaudhry took an evening flight back to the capital and it was unclear whether the rally at Karachi's high court would proceed without it. 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. Reporters saw the bodies of five men lying in the street _ four near a shot-up car and the other next to the red flag of an opposition party. An AP reporter saw MQM supporters calling for ammunition and firing from buildings, reportedly at supporters of the Pakistan People's Party and Jamaat-e-Islami. Opposition supporters were firing back. In another part of the city, private TV network Aaj said MQM supporters were firing at its building and showed footage of a mob setting fire to the vehicles in the network's parking area. 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. Doctors at Karachi's four main hospitals said 27 people were dead and more than 100 injured, many of them from gunshot wounds. A senior security official, speaking on condition of anonymity because he is not authorized to speak publicly, also counted 27 fatalities. 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. The MQM is a partner in a coalition ruling Sindh province, of which Karachi is the capital, as well as in the federal government. 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, 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 cling to 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 measures," 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.