A privately owned Cessna seaplane and a Robinson R44 helicopter collided over the Istrinskoye reservoir near Moscow, Russia, and fell into the water.

Four out of the seven passengers were Armenians, including 2 minors, 8 and 10-year-old Erik and Ofelya Gelchakyans, as well as Larisa, 25, and Pavel, 26, Manukyans, Armenia’s ambassadors to Russia, Oleg Yesayan told Armenian Ministry of Emergency Situations.

Investigators launched a probe into breaches of aviation safety rules.

A source in the Russian civil aviation agency told RIA Novosti state-run news agency that the seaplane pilot did not warn air traffic control about the flight from an aerodrome beside the reservoir.