Two bridges collapsed in different Russian regions bordering Ukraine, derailing trains, killing at least seven people and injuring dozens, Russian authorities said early on Sunday.

Hours later came a report of another bridge collapse, also in western Russia, involving a freight train. A bridge overpass in western Russia collapsed late Saturday, derailing a passenger train underneath and killing at least seven people and injuring dozens, officials and the state news media said.

Explosions caused two bridges to collapse and derailed two trains in western Russia, officials said, without saying what had caused the blasts. In one of the incidents, seven people were killed and dozens were injured.