A powerful car bomb detonated near a residential area in Islamabad on Friday, killing two suspected militants and an officer, police said, raising fears that militants have a presence in one of the country’s safest cities.

At least three police officers and seven passersby were wounded in the bombing.

Friday’s bombing in Pakistan’s capital city happened 15 kilometers ( about 9 miles) from the garrison city of Rawalpindi, home of the military and government spy agencies.

Police said in a statement that the blast happened when police officers spotted the car and ordered the driver to halt for routine checking. Instead of stopping, its driver detonated explosives hidden inside. A female passenger in the car also was killed, Suhail Zafar Chattha, a senior police officer in Islamabad told reporters at the scene.

TV footage showed a burning car as police officers cordoned off the area.

Residents said they saw policemen on motorcycles chasing a car and ordering a man inside the vehicle to come out.

Chattha, the city’s deputy police chief confirmed that account, saying the suspect blew up the explosive-laden vehicle after being surrounded by police officers.

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Pakistani Prime Minister Shahbaz Sharif condemned the bombing and thanked the police.

“Police officers stopped the terrorists by sacrificing their blood and the nation salutes its brave men,” Sharif said in a statement.

No one claimed responsibility for the bombing. Pakistani Taliban have stepped up attacks on security forces since November, when they unilaterally ended a monthslong cease-fire with Pakistan’s government.

The violence comes days after several Pakistani Taliban detainees overpowered their guards at a counterterrorism center in northwestern Pakistan on Sunday after snatching police weapons and taking three officers hostage.

On Tuesday, Pakistan’s special forces raided the detention center, triggering an intense shootout in which the military later said 25 detainees linked to the Pakistani Taliban were killed in Bannu, a district in the Khyber Pakhtunkhwa province and part of a former tribal region.

Three troops and at least three hostages were killed in that incident.

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The government has since stepped up security across the country, based on intelligence reports that the Pakistani Taliban, known as Tehreek-e-Taliban Pakistan or TTP, had dispatched fighters to carry out attacks at public places and police stations.

Pakistani Taliban are separate but allied with the Afghan Taliban, who seized power in neighboring Afghanistan last year as U.S. and NATO troops were in the final weeks of their pullout after 20 years of war. Since then, top TTP leaders and fighters have been hiding in neighboring Afghanistan, though the militants still have relatively free reign in patches of the province.