A bomb planted in a rickshaw killed two policemen and wounded four other people in the northwestern Pakistani city of Peshawar on Tuesday, police and hospital officials said.
The blast targeted a police patrol vehicle at the Kohat Road area of Peshawar and also damaged two other vehicles.
"At least two policemen were killed and two others were wounded," doctor Rahim Jan of state-run Lady Reading hospital told AFP.
Two civilians were also wounded and brought to hospital, he said.
Senior police official Tahir Ayub confirmed the attack and the death toll.
Bomb disposal officials said the bomb weighed up to 12 kilograms (26 pounds) and was rigged in an rickshaw which was detonated remotely when police patrol passed by.
"The bomb was planted in a rickshaw parked on a roadside and was detonated remotely when police patrol vehicle arrived," bomb disposal squad chief Shafqat Malik told AFP.
Last week a suicide bomber assassinated a prominent Pakistani police commander in Peshawar who took a leading role in anti-Taliban operations in the country's troubled northwest.
Peshawar has a population of 2.5 million people and has long been on the frontline of violence blamed on an insurgency led by Taliban militants opposed to Islamabad's alliance with the United States.
Islamist militants have killed more than 4,900 people across Pakistan since government troops raided an extremist mosque in Islamabad in July 2007.