Fires from the countryside had ripped through a naval logistics base in Kolomna, southeast of Moscow, and destroyed office buildings and warehouses and equipment.
The damage was immense - the staff headquarters, financial department, 13 warehouses containing aeronautical equipment and 17 storage areas containing vehicles were destroyed in the blaze.
"I order the ministry of defence to fire a whole number of officers for the disciplinary infringements that were allowed to take place," the president added in televised comments.
Those sacked included the head of the Russian Navy's logistics division Sergei Sergeyev and the head of the Navy's aviation Nikolai Kuklev, Medvedev said.
"If something similar happens in other places and departments, I will act in the same way, without any pity," he added.
The president added that he had called on the armed forces to help protect civilians from the fires across Russia. "Unfortunately, in many cases the ministry is unable to defend itself," he said.
The authorities meanwhile moved to prevent an even greater calamity as wildfires raged within a few kilometres of the country's top secret nuclear research facility in Sarov, a city still closed to foreigners.
Officials said all dangerous nuclear materials had been moved away and over 2,000 emergency services personnel and hundreds of members of the armed forces were sent to Sarov.