According to the government in Moscow, a fire broke out on a Russian military base on the Crimean peninsula and ammunition then exploded.
The fire broke out around 5:15 a.m. in a temporary ammunition depot at the base in the Jankoy district in the north of the Russian-annexed peninsula, according to a statement by the Defense Ministry in Moscow released by the Russian news agencies.
"As a result of the fire, there was an explosion of ammunition."
According to Crimean governor Sergei Aksyonov, two civilians were injured.
The Russian Defense Ministry said the injuries were not serious.
The explosions continued three hours after the fire broke out, Aksyonov said in a video message on his Telegram blog.
"An evacuation is underway, and a five-kilometer security zone is being formed for the safety of residents," he said.
Defense Department, National Guard and Civil Defense forces are deployed.
According to the authorities, the explosion happened in the village of Maiskoye, on the site of a former farm used by the Russian armed forces as an ammunition depot.
A substation for the power supply is also said to have caught fire.
Only on Tuesday a week ago there were heavy explosions at a Russian military base.
According to the authorities, one person was killed in the explosions at the base in Saki near the resort town of Nowofyodorovka.
There were also 14 injured.
Experts believe Ukraine struck the base, destroying several fighter jets.
Kyiv has not officially confirmed the attack.
Russia, on the other hand, claims the explosion occurred because of fire safety violations.
According to the authorities, a Ukrainian drone struck the Russian Black Sea Fleet in the port city of Sevastopol on July 31.
There were injuries then too.