Rescuers are searching a north Siberian lake after a storm caused a steamboat to capsize, five people are reported to have been rescued, local prosecutors said on Wednesday. The boat sank on Tuesday in Lake Pyasino, 80 km (49 miles) from Norilsk, Siberia`s northernmost city above the Arctic Circle. Emergency crews are trying to establish how many people were onboard the boat when the storm hit. Prosecutors and emergencies officials have provided conflicting reports on the number of missing. "Five people survived, seven are missing," the central Investigation Committee said on its website citing preliminary reports. Local emergencies officials, however, said a total of seven people were on board the vessel, and two are unaccounted for. They said five people had left the steamer prior to the accident. "The fate of two is not known, we are trying to establish their identity." Police were informed of the incident following a call from an anonymous caller. Oksana Gorbunova, a spokeswoman for the local prosecutor, said investigators and rescuers were unable to get to the scene immediately due to poor weather. A rescue helicopter only managed to fly to the lake on Wednesday. The steamer is believed to be a private vessel, she said. Pyasino is a large freshwater lake with an area of 735 sq km. Its average depth is 4 meters. It freezes up in October and stays icebound until June.