A bomb exploded on a bus in Pakistan's northwestern city of Peshawar on Saturday, killing at least nine people and wounding seven others, officials said.
"At least nine passengers have been killed and seven injured. Bomb disposal officials told me that it was a timed device," Fazal Wahid, a senior police official told AFP.
Shafi Ullah Khan, another police official, confirmed the attack which occurred as the was bus passing through the city's Matani suburb.
There was no immediate claim of responsibility for the blast, which came hours after militants blew up the election office of an independent candidate in the same region, adding to security fears ahead of historic national polls next month.
A recent wave of terror attacks has fuelled concerns that violence will mar general elections on May 11, which will mark the country's first democratic transition of power after a civilian government has served a full term in office.
Pakistan says more than 35,000 people have been killed as a result of terrorism in the country since the 9/11 attacks on the United States.