The ALH Dhruv chopper had taken off from Bareilly.
Sub Divisional Magistrate, Sidhauli, A K Srivastava said that the chopper was engulfed in fire as it crashed in Manipurwa in Ataria area.
"A helicopter of airforce has crashed here. It is engulfed in fire and it is feared that all on board might have died," Srivastava told PTI.
Attempts were underway to douse the fire.
Senior officials of district administration and police have reached the spot.
District Magistrate, Sitapur, JP Singh said that the helicopter took off from Bareilly and was going towards Allahabad.
"According to our information, there were seven persons on board the chopper including pilot and co-pilot. As per the reports received from officials, no one is appeared to have survived," he said.
Sitapur is nearly 160 km from Bareilly and over 90 km from Lucknow.