Islamabad, Jan 16 (IANS): At least seven people were killed and 55 injured in a blast in a tableeghi markaz (preaching centre) in Pakistan's northwest Peshawar city Thursday evening, hospital sources and police said.

Medical Superintendent of Lady Reading Hospital Dr. Arif said that they received seven bodies and over 55 injured people while ambulances are continuously bringing in more wounded people, according to Xinhua.

Senior Superintendent of Peshawar Police Najeeb-ur-Rehman confirmed that the blast happened on the first floor of the building when over 800 people were offering evening prayers.

The incident happened in the city's biggest such centre in the densely populated Charsadda Road area of Peshawar, the capital of the country's Khyber Pakhtunkhwa province.

The injured have been shifted to various hospitals in the city, including Lady Reading Hospital where emergency has been declared.

Though the nature of the blast has not been determined by officials or bomb disposal squad yet, political leaders and hospital sources are making various speculations about the blast.

Doctors at Lady Reading Hospital said that judging from the wounds of the injured people, it seemed that they have been hit by explosive materials.

Some eye witnesses said there were a large number of cylinders inside the preaching centre for heating and the blast was triggered by the cylinders exploding.

No group has claimed responsibility for the attack yet.

Police cordoned off the area and started a search operation.

Prime Minister Nawaz Sharif condemned the blast and directed the hospital administration to provide the best possible treatment to the injured.