Another 12 persons were seriously injured when the bus collided head-on with the truck on Gonda-Bahraich road near Chilwaria village and caught fire last night.
A magisterial inquiry has been ordered, District Magistrate Kinjal Singh said.
Superintendent of Police, Bahraich, B P Kanaujia said that a total of 16 bodies have been recovered including that of seven women.
12 seriously injured persons have been admitted to a district hospital and some have been sent to Lucknow for treatment.
Though Kinjal declined to specify how many people were inside the 54-seater bus, which was carrying the pilgrims from Ambedkar Nagar to Ajmer Sharif, Chief Development Officer of the district Sukhlal Bharti said the bus was carrying about 60 to 70 people.
However, Mehdi Raza, one of the rescued passengers, said that there were about 80 people in the bus when the accident took place.
Kinjal said the bus caught fire possibly due to the explosion of a cooking gas cylinder inside the vehicle.
However an inquiry will establish the cause, she added.
Rescuers had used gas-cutters to cut open the twisted metal of the bus to pull out bodies and survivors from inside the vehicle.
