Story highlights Three police officials, one of them senior, are killed in the blast

The attack wounds 31 people, a police officer on the scene says

Peshawar, where the attack took place, is a gateway to Pakistan's restive tribal region

A suicide bomber killed himself and five other people, including a senior police official, in an attack in the center of the northwestern Pakistani city of Peshawar on Wednesday, a police officer at the scene said.

Three police officials and two civilians were killed in the explosion, said Imran Shahid, the police officer. Thirty-one people were wounded, he added.

Peshawar is the capital of Khyber Pakhtunkhwa province and the gateway to Pakistan's tribal region, which is largely ungoverned and has a strong militant presence.

For more than a decade, Peshawar has been on the front line for the Pakistani government's fight with militant groups such as the Taliban. A major terrorist attack near the U.S. Consulate in Peshawar in April 2010 killed at least 25 people.

The area where the attack took place Wednesday is known as the Storytellers Market. It is one of the oldest markets in the country and predates the creation of Pakistan in 1947.