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. 

The first bridge, in the Bryansk region on the border with Ukraine, collapsed on top of a passenger train on Saturday, causing the casualties. The train’s driver was among those killed, state-run Russian Railways said.

Hours later, officials said a second train derailed when the bridge beneath it collapsed in the nearby Kursk region, which also borders Ukraine.