Russian forces have now seized two Ukrainian nuclear power plants and are advancing toward a third, Ukraine’s president said during a call with U.S. senators Saturday.

According to the report, Volodymyr Zelenskyy said the third plant currently under threat is the Yuzhnoukrainsk nuclear power plant, located 75 miles north of Mykolaiv, one of several cities the Russians were trying to keep encircled Saturday. One of the plants under the Russians’ control is the Zaporizhzhia nuclear plant in the southeastern city of Enerhodar, the biggest nuclear power plant in Europe.

The other is Chernobyl, which is not active but is still staffed and maintained. Previous Russian shelling sparked a fire at the Zaporizhzhia plant that was extinguished without a release of radiation. Technical safety systems are intact and radiation levels are still normal at the Zaporizhzhia plant, according to the country’s nuclear regulator, the International Atomic Energy Agency said Saturday.

The developments all pointed to a worsening crisis for Europe and the world as President Vladimir V. Putin of Russia showed no inclination to soften his goal of taking control of Ukraine, the former Soviet republic of 44 million that is now at the center of an intense new Cold War between Russia and the West. As Russian troops moved deeper into the Ukrainian heartland, the number of civilians headed toward the western border to escape the onslaught increased sharply.

In the western city of Lviv, the train station was swamped with desperate civilians seeking refuge from the Russian assault. The rising flight of civilians came as Ukraine said Russian forces were now occupying the Zaporizhzhia nuclear facility after an early-morning battle and fire there had raised worldwide alarms. It said that all of the site’s power units remained intact and that no changes in radiation levels had been observed.