The International Atomic Energy Agency said its staff heard loud explosions near Ukraine’s Zaporizhia nuclear power plant on Sunday, coinciding with reports of a drone attack on the plant’s training center, the agency’s director general said.

The agency could not confirm what the situation is at the scene, said Rafael Mariano Grossi.

“The IAEA is aware of reports of an alleged drone attack on the ZNPP training center that occurred today, just outside the perimeter of the site,” Grossi said in a statement.

“Reports say there were no casualties and no damage to nuclear power equipment.”