Ammunition being stored in southern Russia near the border with Ukraine caught fire on Tuesday, the second such incident in a week, and a local official said high temperatures were to blame.
Vyacheslav Gladkov, the governor of Belgorod region, said people near the village of Timonovo were evacuated after the ammunition started to spontaneously combust. No one was injured, he said in a statement.
Last week inhabitants of Timonovo and Soloti, 15 km (9 miles) from Ukraine, were evacuated after a nearby ammunition storage depot caught fire. It was not clear from Gladkov's comments whether Tuesday's blaze had taken place in the same depot or among ammunition that had been moved.
Gladkov has in previous months blamed Ukrainian forces for a series of blasts in and around Belgorod, which is around 650 km (400 miles) south of Moscow.
Kyiv generally avoids claiming responsibility for explosions in Russian-occupied territory, sometimes suggesting sardonically that carelessness is to blame.
"In a few months we will find out whether Russian ammunition can explode because of the cold," Ukraine's defence ministry said in a tweet on Tuesday.
"The five main causes of sudden explosions in Russia are: winter, spring, summer, autumn and smoking."
(Reporting by David Ljunggren; Editing by Cynthia Osterman)