While Geo said it was a gas cylinder blast, at least two other local TV channels, namely Dunya and Waqat, said it was a suicide blast.
There is no official confirmation about the nature of the blast yet.
An investigation into the nature of the blast is still underway, reports said.
The blast reportedly took place at about 5:10 p.m. local time inside a preaching center on Takht Band Road in Mingora, a small town in Swat District, some 115 kilometers northwest of the country's capital Islamabad.
A large number of people were present for Friday evening prayer at the center when the blast went off, reports said.
Eyewitnesses told Geo that the blast was heard from the kitchen of the preaching center, leaving many windowpanes and doors of the center smashed and destroyed.
The explosion created a severe panic among the attendees at the center, they said.
Police and rescue team rushed to the site after the blast and all the injured have been shifted to Saidu Sharif Hospital in Mingora.
Hospital sources said the death toll may further rise as some of the injured are still in critical condition.