The bombing hit the Hangu area, just outside the tribal regions along the Afghan border where Al-Qaeda and Taleban fighters have long operated, said senior police official Rasheed Khan.

A bomb hidden in a vehicle in a residential area where a small police station was located went off as a police vehicle carrying officers drove by, Khan said. Three police and four civilians died. The blast also wounded 30 people and damaged around a dozen houses, he said.

Gunmen in the nearby Khyber tribal region ambushed another group of police, shooting and killing six, said local government official Farooq Khan. The police had been driving to a security checkpoint in the area when they were attacked.

The US has pressed Pakistan to eliminate hide-outs used by Islamist insurgents, saying they threaten not only American and NATO troops in Afghanistan but also the stability of nuclear-armed Pakistan itself.

On Wednesday, militants killed the only Christian minister in Pakistan’s government. Shahbaz Bhatti was apparently targeted because he had urged Pakistan to reform its harsh laws that impose the death penalty for insulting Islam.

Prime Minister Yousuf Raza Gilani on Thursday declared three days of official mourning for Bhatti and ordered flags lowered to half-staff on Friday. He and others condemned the killing but stopped short of mentioning the blasphemy laws, apparently fearful of Islamist backlash.

Bhatti was the second Pakistani politician killed in two months over the blasphemy issue. On Jan. 4, Punjab Gov.

Salman Taseer was shot dead by one of his own bodyguards who disagreed with his view that the laws need to be changed.

Even as Pakistan strives to stop militancy, it finds itself challenged on other fronts that threaten to bring down the weak civilian government, notably a struggling economy.

After months of delaying it, the government this week raised fuel prices 9.9 percent because of spikes in international markets spurred by strife in the Middle East and North Africa.

The price increase has angered opposition parties and even some allies of the ruling party, who have urged the government to reverse the hike. Earlier this year, the ruling party narrowly avoided a collapse of its governing coalition over another attempted fuel price hike.

Public transportation workers in the southern port city of Karachi went on strike over fuel prices Thursday. The strike crippled much of the city, which is Pakistan’s most populous with 18 million people as well as its main economic hub. Many schools were closed.

Irshad Bukhari, the president of the Karachi Transport Union, said more than 25,000 buses and other vehicles stayed off the roads. Millions of commuters could not travel as a result, he said, expressing confidence they supported the strikers.

“People respond to our strike call because it is not only the transporters’ problem but also the people who have to bear the cost of higher fares,” he said.