"According to preliminary reports the explosion killed three and left another two injured. In addition another three people were still missing " Tass news agency quoted a regional law enforcement source as saying reported Xinhua news agency.
Interfax news agency earlier reported that seven people died in the explosion while Sputnik news agency said four people were hospitalised.
No official death toll has been released so far. Information on the possibility of additional victims is being verified according to a statement by the Russian Emergencies Ministry s Nizhny Novgorod regional division.
Fire rescue units are in the process of putting out the fire caused by the explosion the statement said.
--IANS anp/bg
