Alexander Bogomaz, the regional governor of Bryansk, said on the Telegram messaging app that seven people died in the collapse, which occurred in the Vygonichskyi district near a federal highway.
"There are seven dead as a result of the collapse of a bridge onto railway tracks," he wrote. More than 60 are injured, including three children, with one in critical condition.
What do we know about the bridge collapse?
The train came off its tracks while it was en route to the Russian capital of Moscow from Klimov in the country's west, Moscow Railways said in a statement.
It initially said the bridge had been damaged "as a result of illegal interference in transport operations" without elaborating, but the post was later removed.
Bogomaz later confirmed reports about an explosion at the bridge.
"There was an explosion on the bridge on the route while the Klimovo-Moscow train was travelling, with 388 passengers on board," he said on state television.
Russia's Investigative Committee also said in a statement that "a road bridge collapsed as a result of a blast" in the Bryansk region at 10:50 pm (1950) on Saturday.
The disaster area is about 100 kilometers (62 miles) from the Ukrainian border. Ukraine has not commented on the bridge collapse or the derailed train.
Second bridge collapses in Kursk
Just hours later, a second bridge collapsed in the border region of Kursk, which borders Ukraine. The Kursk region was the site of a Ukrainian incursion into Russia last August.
Russian investigators said explicitly that both bridges were blown up.
"The incidents have been classified as acts of terrorism," Svetlana Petrenko, a spokeswoman from Russia's Investigative Committee, was quoted as saying by the state RIA Novosti news agency.
Kremlin spokesperson Dmitry Peskov said that Russian Vladimir Putin had been briefed on explosions at the two bridges.
Since Russia launched its full-scale invasion of Ukraine over three years ago, Russia's border regions, including Bryansk, have faced border shelling, drone strikes and covert raids from Ukraine.
