Russian strikes killed 25 civilians and injured at least 50 others overnight in the Ukrainian province of Zaporizhzhia, Ukraine's prosecutor general said.

Why it matters: The attack was one of the deadliest targeting Ukrainian civilians in recent weeks, according to the New York Times. It comes as the Kremlin plans to declare the area a part of Russia Friday following a series of sham referendums that have drawn wide condemnation from western governments.

• The strikes killed and injured scores who were waiting at a bus stop and checkpoint, the Times reports.
• In a separate strike, three were killed and at least 19 were injured in a neighborhood in Mykolaiv.

The big picture: Russian President Vladimir Putin is poised to formally annex four Moscow-occupied areas of Ukraine on Friday: Donetsk, Luhansk, Zaporizhzhia and Kherson.

• Ukrainian President Volodymyr Zelensky has warned that annexation would end diplomatic negotiations between the countries, and most western governments — including the U.S. — say they won't recognize the territory as Russian.
• While Russia does not entirely control the four regions, the move will enable Moscow to claim it is no longer attacking the Ukrainian territory, but instead defending its own.

Go deeper: Russia vows "full protection" to territories annexed from Ukraine