In a similar attack in Peshawar, a suicide bomber struck a neighbourhood housing
government buildings and a church.
Liaquat Ali, the city police chief, said the attacker walked up to a checkpoint and detonated his explosives when a police officer asked him to stop.
More than a dozen were injured in the explosion.
Pakistan has stepped up security during the holy Muslim month of Muharram, which is often marred by sectarian violence between the country's Sunni Muslims and its Shia minority.
Muharram is especially important for Shia. They stage processions to mark Ashoura, an event in which they mourn the death of Imam Hussein, the grandson of Prophet Muhammad.
A wave of attacks have occurred in Pakistan since October, as fighters apparently retaliate for an army offensive against the Taliban.
The attacks have killed more than 500 people.
About twenty bomb blasts have struck Peshawar in the last three months, most of them blamed on Taliban fighters.
A suicide bomber attacked a journalists' club in the city on Tuesday, killing three people.
Eleven people were killed when a bomber struck outside a court on December 7.
On October 28, a huge car bombing destroyed a market and killed 125 people.