At least 11 children and one adult have died in a storm on Lake Syamozero in Russia's north-western region of Karelia near the Finnish border, an Investigative Committee official told TASS news agency on Sunday.
Three boats full of 47 children from a summer camp, and their four adult instructors, had gone out Saturday on the lake, Vladimir Markin was quoted as saying.
Local Culture Ministry official Yekaterina Biktimirova said the children were ages 12 to 15. "At night, they were caught in a storm. We already know about some victims," she added.
Twelve bodies had been found, the local emergency service told TASS, adding that four people were still missing and rescue operations were under way, with 36 people having already been saved.
Several helicopters were sent to the site and more than 60 people were involved in search operations.
Representatives of the Moscow authorities, psychologists and doctors were heading for Karelia, TASS reported.
"A big tragedy happened in Karelia," Moscow Mayor Sergei Sobyanin tweeted. "I offer condolences to relatives and friends."