PESHAWAR: Gunmen on Friday ambushed police ferrying terror suspects to dental treatment on a university campus, killing three officers and driving off with the detainees, police said. The detainees included a Taliban commander.

The attack happened at the University of Peshawar where police had taken the detainees from the northwestern city's central jail.

“They were taken to hospital for a dental check-up. The gunmen fired at them when they returned from the hospital,” Peshawar police chief Imtiaz Altaf said.

“The prisoners were arrested under terrorism charges. The gunmen came on two motorcycles and a car, and escaped with them after killing three policemen and injuring one,” said police official Mohammed Ijaz.

Security officials told AFP on condition of anonymity that eight to 10 gunmen had been lying in wait outside the dental college.

Peshawar, a teeming city of 2.5 million, is on the front line of a Taliban insurgency and borders Pakistan's tribal belt that Washington calls the global headquarters of Al Qaeda.

On Thursday, a female suicide attacker and a separate handcart bomb also targeted police in the city, killing seven people in the first deadly attacks on the northwest during the month of Ramazan.