The Ukrainian military said saboteurs have blown up an ammunition dump in the east of the country on March 24.
A string of explosions rent the skies near the town of Balaklia, where about 150,000 tons (138,000 tonnes) of tank ammunition was stored.
Rescuers evacuated people from nearby villages, about 62 miles (100 kilometers) from the frontline of Ukraine’s conflict with Russian-backed separatists.
About 20,000 people were brought to safety. No one was hurt.
Kyiv said the Russian military or separatists are likely to be responsible. The defense minister said it may have been a drone attack or timed explosive. Some people at the base claim they heard the sound of an aircraft moments before the first blasts.
Officials said security around other bases is being beefed up.