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

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.

A train derailed in Russia, killing seven people and injuring 30 more. Authorities are investigating the cause.