At least 16 people were killed across Ukraine, Russian-occupied areas and Russia Sunday as the two neighbors traded military strikes on the 40th anniversary of the Chernobyl nuclear disaster.

The exchange of attacks comes amid renewed warnings over the attacks near the nuclear plant during Moscow’s more than four-year invasion.

The death toll from Russian drone and missile strikes on the city of Dnipro rose to nine, regional head Oleksandr Hanzha said Sunday.

One man was killed in a Ukrainian drone strike on the port city of Sevastopol, in Russian-occupied Crimea, Moscow-installed authorities said Sunday.

Russia annexed the peninsula from Ukraine in 2014, a move that most of the world considered illegal and has used it as a staging and supply point during the war.