QUETTA/DERA ISMAIL KHAN, Pakistan: A bomb ripped through a bus full of Shi’ites in western Pakistan and killed at least 22 people on Tuesday, police said, extending a spate of sectarian attacks that have shaken the South Asian nation.

The attack took place at Dringhar village on the Pakistan-Iran highway some 60 km west of Quetta, Baluchistan’s capital.

Pakistani fighter jets pounded militant positions overnight in the country’s northwest following a Taleban bombing campaign against security forces, military officials and residents said Tuesday. The strikes are likely to hamper the government’s efforts to hold peace talks with the Pakistani Taleban.

There were conflicting claims about who was killed in the air strikes which took place in North Waziristan, a stronghold of the Pakistani Taleban as well as other militant groups. A military official said the strikes targeted militants and killed 25 of them. The official spoke on condition of anonymity.

But at least two residents reached by telephone in North Waziristan said civilians were among those killed in the airstrikes. They said many residents slept in the open out of fear their homes might be hit.

“How would the jet fighters know who is living where and who is a militant and who is a civilian in the dark of the night,” said Habib Dawar who lives in Mir Ali, one of the main towns in North Waziristan.

Also Tuesday, gunmen in a pair of attacks minutes apart struck two teams of polio workers in the southern city of Karachi, killing three members of the teams and wounding a fourth before fleeing, police said. Police official Pir Mohammad Shah said two female and a male worker were killed in the attacks in Karachi, the capital of southern Sindh province.

The vaccination campaign was cancelled following the attacks, said health official Zafar Ejaz. No group has claimed responsibility.

The area where airstrikes occurred is remote and dangerous for journalists to access, making it impossible to independently verify the conflicting casualty claims.

The overnight strikes came after two days of attacks claimed by the Pakistani Taleban killed 34 security personnel.