Authorities in annexed Crimea declared a regional state of emergency on Tuesday as a wildfire that began last week following a Ukrainian drone attack continued to grow in size.

The blaze broke out last Wednesday in a forest nature reserve near the resort city of Yalta and expanded from just over 3 hectares (8 acres) to 50 hectares (124 acres) in the span of three days.

Emergency officials have not officially confirmed the cause of the fire, but reports citing NASA satellite imagery said it started on the night of a Ukrainian drone attack on Yalta.

The Interfax news agency reported that Sergei Aksyonov, the Kremlin-installed head of Crimea, declared the wildfire a cause for a “regional natural emergency.”

The emergency zone boundaries have been set within the Yalta Mountain-Forest Nature Reserve. Police were advised to block roads leading into the nature reserve to keep people out of danger.