Ukraine has said it attacked naval targets and port infrastructure in Crimea, in one of its biggest strikes on the Russian navy's Black Sea fleet.
Russia earlier claimed Ukraine had launched 10 missiles and three unmanned boats in the attack.
It caused a large fire at a Sevastopol shipyard which left 24 people injured, Russia said.
The Moscow-installed governor claimed most of the weapons were intercepted but that two ships had been damaged.
Ukraine has strongly implied western-supplied cruise missiles were used in the attack, one of the biggest on the Black Sea fleet since the war started.
Unmanned vessels, known by many different names including sea drones and drone boats, operate on or below the water. They usually have built-in explosives and cameras that feed directly back to the person controlling them.
A photo shared by Sevastopol Governor Mikhail Razvozhayev on Telegram shows flames engulfing what appears to be a ship at a port as he stands speaking into his phone.
It is thought to be in an area where ships were undergoing repairs.
A large landing ship, named the Minsk, and a submarine, called the Rostov-on-Don - both thought to be in dry dock - are said to have been damaged. This makes it one of Ukraine's most significant attacks so far on the Black Sea fleet.
According to state-run Ria Novosti news agency, the Russian defence ministry said both vessels will be fully repaired and continue in normal service.