Four people were killed and 28 others wounded Saturday in a bomb explosion on Saturday in Pakistan’s northwestern city of Peshawar.

Four people were killed and 28 others wounded Saturday in a bomb explosion in Pakistan's northwestern city of Peshawar.

The explosion took place inside a mosque while people were performing afternoon prayers in the densely populated Mohalla Baqar Shah area of Peshawar city.

"The bomb, which was planted inside the mosque, went off killing four people and wounding 28 others," senior local police official, Imran Shahid, told AFP.

He said that there were up to 40 people present in the mosque at the time of the explosion.

A spokesman for Peshawar's Lady Reading Hospital, Jameel Shah, also confirmed the casualties: "We have received four dead bodies and over 20 wounded people, and the condition of two patients is very serious."

Peshawar is vulnerable to bomb blasts and Taliban attacks as it runs into the semi-autonomous tribal belt, considered a safe haven for Taliban, Al-Qaeda and other insurgents fighting both in Pakistan and across the border in Afghanistan.