At least four people were martyred while five sustained injuries during an explosion inside a mosque located in the Doaba police station in Khyber Pakhtunkhwa’s Hangu on Friday. The incident took place within the parameters of Police Station Doaba during Friday sermon, said police. “The roof of the mosque caved in due to the impact of the explosion,” the police official stated, adding that nearly 30 to 40 people were reported to be stuck under the rubble.