The blast occurred at Chinispur village under Beru gram panchayat in Ketugram 1 block on Tuesday night.
Tuesday's explosion in Lebanon's port city of Beirut killed 135 people and injured about 5,000 people.
The mishap occurred at the fifth unit of the thermal power station-II (210 MW x 7) when workers were in the process of resuming operations this morning.
NLC India Chairman and Managing Director Rakesh Kumar told PTI that the injured persons were immediately shifted to Kaveri Hospital in Trichy where they are undergoing treatment.
Reports said that many more could be buried under the debris which was now being removed.
Among those killed, six were Indians, including a Keralite who was identified as P S Razina Khadar, 58, a native of Mogralputhur in Kasaragod district.
Survivors were taken to 16 hospitals with 640 people being treated for injuries. Thirty-two of them were critically injured.
Investigations are on and it was yet to be ascertained whether the explosion was caused by a grenade or an improvised explosive device.
Zhangjiakou, a city about 156 km northwest of Beijing, is set to host the 2022 Winter Olympics alongside the capital.
The explosion was reported outside a fruit shop on the ground floor of the building in the congested Kazipara area under the jurisdiction of Dum Dum Police Station around 9 am.