Six children were among 10 people killed when an all-terrain vehicle capsized while crossing a remote Siberian river, authorities said Friday.

Apparently, members of two families, they are thought to have drowned in the Siberian region of Tyva bordering Mongolia, the head of the region said.

“Ten people died as they attempted to cross the Shui river in their UAZ-469,” Sholban Kara-ool said in a post on Facebook, referring to an offroad light utility vehicle that seats up to seven people. In a separate statement, investigators said locals found ten bodies in a vehicle that appeared to have capsized in the water.

Russia’s Investigative Committee, which probes serious incidents, said it has opened a criminal probe into a possible violation of traffic safety rules. Road accidents are common in Russia, where many people ignore traffic rules.