President Serzh Sargsyan sent a letter of condolences to his Russian counterpart Vladimir Putin over the collapse of a boat that left over a dozen dead.

Fourteen people, mostly children, died when a storm caught a boating party on Lake Syamozero in northern Russia's Karelia region, BBC News reports.

Most of the 37 survivors reached an island in the lake while others were found in a village, some of them washed ashore.

The children were on holiday from Moscow, and Mayor Sergei Sobyanin sent doctors and psychologists.

Four people have been arrested on suspicion of safety violations.

"A great tragedy has occurred in Karelia," the mayor tweeted.

"My condolences to their families and friends."