Pakistan's president Pervez Musharraf has appealed for calm following the deaths of at least 34 people in clashes between pro-government and opposition activists over the arrival of the country's suspended top judge yesterday.
The suspension of Chief Justice Iftikhar Chaudhry on March 9th has outraged the judiciary and the opposition and has become the most serious challenge to President Pervez Musharraf's authority since he seized power in 1999.
The opposition Pakistani People's Party said the city of Karachi was under siege by supporters of the pro-government Muttahida Qaumi Movement (MQM), which runs Pakistan 's biggest city.
Yesterday was declared a public holiday in Karachi and normal traffic was largely absent from the streets, where thousands of paramilitary troops and police were on patrol.
Heavy gunfire erupted outside the airport and elsewhere as gunmen clashed and smoke billowed from more than 100 burning vehicles.
MQM activists clashed with members of the Muttahida Majlis-e-Amal, an opposition alliance of religious parties, and the PPP in several parts of Karachi, which has for years been riven by bloody political feuding.
Television showed pictures of men with AK-47 assault rifles firing from behind cars. A man with a neck wound was shown crying in a bus, another wounded man lay gasping in a pool of blood.
Private Aaj Television said its office had come under fire and police said sporadic firing was still going on after dark.
Many roads including the one from the airport were blocked by trucks, buses and containers overnight in an apparent bid to disrupt Mr Chaudhry's visit to the capital of Sindh province.
"It is state-sponsored terrorism. The Sindh government is responsible but we are not going to back off," said PPP spokeswoman Sherry Rehman.
Provincial government officials had warned of violence in the volatile city and appealed to Mr Chaudhry to postpone his trip. But he went ahead and arrived on a flight from Islamabad.
Hours later, he was still in the airport VIP lounge, still hoping to meet his supporters, one of his lawyers said, though authorities had urged him to leave.
"The chief justice should think about his decision and go back to Islamabad," said top provincial Interior Ministry official Waseem Akhtar.
Mr Chaudhry denies wrongdoing and has refused to resign in the face of charges of misconduct.
His visit to Karachi was meant to be the latest in a series of protests by the opposition and lawyers to press for his reinstatement.