KARACHI, Pakistan -- Security forces were ordered to shoot gunmen on sight Friday in Pakistan's largest city, as four days of violence left at least 71 people dead and prompted political leaders to call for a day of mourning that shut businesses and kept public traffic off the roads.
This week's violent spate in Karachi was among the worst this year for a city that has long been a hotbed of ethnic, sectarian and political tensions. It came just days after the city's most powerful political party, the Muttahida Qaumi Movement, said it was leaving the federal ruling coalition to join the opposition.
Such political shifts involving the MQM have historically been accompanied by violence in Karachi, though it and other parties active in the city deny stirring the tensions.
At least 34 people died on Thursday alone, when gunmen strafed buses and went on shooting sprees in several neighborhoods.
The order to shoot suspects on sight reflected the authorities' desperation to bring the spiraling violence under control.
Sharjeel Memon, the Sindh province information minister, said the order was aimed at "any armed miscreant" encountered by police, Rangers and other security troops.
Karachi is a port city of 18 million people that lies on the Arabian Sea. In any given year, it can easily witness more than 1,000 violent deaths.
According to the Human Rights Commission of Pakistan, 1,138 people have been killed in Karachi in the first six months of this year. Of those, 490 were victims of so-called targeted killings, which are often linked to political, ethnic and sectarian rivalries.
The commission's figures did not include those reported in recent days.
Relatives wept over the bodies of loved ones in morgues and hospitals Friday. The smell of burning tires wafted through some streets.
"People are stuck at home, their food and rations are running out," Karachi resident Mohammad Shahid said. "Where is the government? Where are the police?"
Many of the killings that began Tuesday appeared linked to political and ethnic turf battles, said Saood Mirza, the Karachi police chief, who also confirmed the latest death toll. Some of Karachi's leading political parties have been formed along ethnic lines.
Authorities have rounded up dozens of suspects, standard practice in such crackdowns in Pakistan. Most of those detained are usually freed for lack of evidence. Around 1,000 members of the Frontier Constabulary, a paramilitary police force, were expected to be deployed to help security.
The MQM party called for a "day of mourning" Friday. That prompted shutdowns across much of the city, with roads and commercial areas largely deserted. However, occasional gunshots could still be heard in some areas, and the police chief said 18 more people were killed.
The MQM party is accused of links to some of the armed gangs in the city, as are its rivals, the Pakistan People's Party and the Awami National Party. The MQM was part of the ruling federal coalition, but recently decided to join the opposition. The ANP and the People's Party are members of the federal ruling coalition.
One of the party's top leaders, Raza Haroon, suggested Friday that the political machinations had prompted the violence, although police have avoided blaming any particular party.
"We are being punished for leaving the coalition government," he said.
U.S. Ambassador to Pakistan Cameron Munter expressed deep concern over the escalating violence in Karachi and in a statement on Friday called "on all parties to refrain from further violence and work toward a peaceful resolution of differences."
The federal Interior Minister, Rehman Malik, a member of the ruling People's Party, said the death toll may be as high as 85. He said he'd sent a message to the MQM and the Awami party that said, "Let's have a ceasefire."
Pakistan has seen violent crime rise alongside Al Qaeda and Taliban-led Islamist militancy in recent years, with Karachi bearing much of the brunt.
Also Friday, a government administrator said Pakistani troops backed by jets killed 11 suspected Taliban militants in the northwest tribal region of Kurram. That brings to 45 the number of suspected insurgents killed in Kurram since the army began an offensive there Sunday, Javed Ullah said.
The Pakistani army's operation in Kurram follows reports that the feared Afghan Taliban militant group, the Haqqani network, is using the territory to help it launch attacks against NATO forces across the border.
But the Pakistani military is more likely focused on Pakistani Taliban militants who have declared war against the state and its security establishment. Many analysts believe Pakistan is hesitant to target the Haqqanis -- as demanded by the U.S. -- because of historical ties to the group.
Information from Kurram is nearly impossible to verify independently because the area is remote and dangerous. It is also unclear how the Pakistani authorities distinguish between insurgents and civilians killed during their airstrikes and other battles.