Rival political groups have clashed in Karachi, killing some 34 people and injuring at least 120, in Pakistan's worst political violence in years.
Roads were blocked by debris after violent clashes
Chief Justice Iftikhar Muhammad Chaudhry, suspended from his job by President Pervez Musharraf, had flown in to address a rally.
But the gunfire stopped him leaving the airport, and he abandoned his plan.
Opposition groups blamed the pro-Musharraf MQM party of organising the unrest, but it denied the claim.
Since his suspension on charges of "misuse of authority", Mr Chaudhry has become the focus of widespread opposition to the government of Mr Musharraf, who took power in a coup in 1999.
The BBC's Barbara Plett in Islamabad says opposition parties have turned Mr Chaudhry's case into a campaign against military rule.
His supporters say that Mr Musharraf wants the judiciary headed by a lawyer whom he can more easily manipulate.
In the worst violence, supporters of Muttahida Qaumi Movement (MQM) and activists from the Pakistan People's Party (PPP) of former Prime Minister Benazir Bhutto fought gun battles for an hour.
The private Aaj TV channel showed pictures of its office under fire.
9 March: Musharraf suspends Chaudhry for "misuse of authority"
16 March: Violence at pro-Chaudhry rally in Islamabad
3 April: Chaudhry appears before private session of court
6 May: Large rally in support of Chaudhry in Lahore
12 May: Violence in Karachi, ahead of planned rally
"We are under attack," said journalist Talat Hussain on air, sheltering behind a wall.
"We have seen no security force. No-one has come to help us."
Reporters from the Associated Press news agency said they saw five bodies lying in the street, four next to a car which had been raked with gunfire.
At least 20 vehicles were set on fire in the violence, AP said.
"It is state-sponsored terrorism. The Sindh [province] government is responsible but we are not going to back off," said Sherry Rehman of the PPP.
An MQM spokesman denied his party was involved in the violence at the TV station.
A lawyers' spokesman told the BBC that bar association members in Karachi had also been attacked by MQM activists in various parts of the city.
The lawyers say that activists attacked them and prevented them from entering the Sindh High Court premises where Mr Chaudhry had been due to speak.
Trapped at airport
Mr Chaudhry flew from Islamabad to Karachi on Saturday morning, planning to address a rally in the city.
But after landing, he was unable to leave the airport, because roads into the city were blocked.
After several hours, Mr Chaudhry departed back to Islamabad.
Mr Musharraf has ruled out a state of emergency, and appealed to the country to stand united and peaceful.
"If you really feel sorry over what has happened in Karachi, then stop these protests," he told supporters at a rally in Islamabad later in the day.
In Islamabad, the ruling party organised its own show of street power, bussing in thousands of people from across the province to support Mr Musharraf.
So in both Islamabad and Karachi, our correspondent says, there have been attempts to check the momentum of the chief justice's campaign, but it is not clear what has been achieved.