The dry dock housing Russia’s only aircraft carrier, the Admiral Kuznetsov, sank late Monday night, damaging the troubled carrier, injuring four, and potentially killing one ship worker.

One worker remains missing, as search and rescue teams comb the frigid waters of the Kola Bay near Murmansk. The carrier itself — which has been undergoing long overdue repairs and upgrades that hoped to see Russia’s flagship return to service by 2021 — suffered a 15-20 foot gash on the flight deck as one of the dry dock’s cranes collapsed as the dock itself sank. In all, 71 people were evacuated from the Admiral Kuznetsov and its dry dock, though they were able to ensure the carrier itself would not go under with the dock before evacuating.

“It’s obvious that when a 70-tonne crane falls onto the deck, it’s possible that there could be such damage. We consider the damage to be insignificant.” Alexei Rakhmanov, head of Russia’s United Shipbuilding Corporation, told reporters.

Russian officials have already stated that a criminal investigation has been launched with an eye toward violations of any safety protocols that may have led to this internationally embarrassing incident. So far, there has been no word on what effect this incident may have on the carrier’s expected return to service, but it stands to reason that the loss of one of the world’s largest floating docks, in conjunction with Russia’s struggling economy, will mean it will be years before the Admiral Kuznetsov is once again operational.