At the scene of Mariupol theater bombing, Russia prepares for a parade

City officials estimated at the time that as many as 300 people were killed in the March 16 airstrike. An Associated Press investigation, published Wednesday, put the number killed at close to twice that, based on the accounts of survivors and rescue workers. The report also drew on detailed floor plans of the Mariupol Drama Theater and photos and videos taken before and after the attack.

A white flag had been tied atop the building before the airstrike, and the word “children” was painted in Russian on the ground along two sides.

Ukraine’s defense intelligence agency said Wednesday that Russia was planning to turn Mariupol into a center of “celebrations” on May 9. That date, known as Victory Day, marks Russia’s role in defeating Nazi Germany. “To this end, the city is urgently cleaning the central streets of debris, the bodies of those killed and unexploded ordnance,” the agency said.