A roadside bomb killed at least seven policemen and wounded 22 people in the southwestern Pakistani city of Quetta on Wednesday, Dawn newspaper reported.

Sources in the security forces claimed that the bomb exploded when a vehicle carrying 35 policemen was passing the area.

Balochistan province Home Minister Sarfaraz Bugti, visited the site of the blast and told reporters that those attacked were elite officers. “The car was going as per routine and it was hit. It appears to be a vehicle borne attack, and we are still identifying whether it was by a suicide bomber or planted explosives,” Bugti was quoted as saying by Al Jazeera.

Security forces have cordoned off the area, and are conducting a security sweep, Dawn said.

No group has claimed responsibility for the blast yet. Attacks have often been carried out in Quetta by groups such as the Tehreek-e-Taliban Pakistan and armed ethnic Baloch separatists fighting for independence from Pakistan.

A suicide attack targeting an Army vehicle in the city on August 13 (pictured above) left 15 people dead and 32 others injured.