The death toll among Kazakh servicemen swept out to sea during a naval military exercise in the Caspian Sea reached 12, the administration of the Caspian Mangystau Region of Kazakhstan said Thursday.

“According to updated data, during the performance of a combat training task, due to a sharp deterioration in meteorological conditions and strengthening wind, 17 people were swept out to sea, 12 of them died, three were rescued. The search for the remaining two servicemen continues,” it said in a statement.

The Defense Ministry said earlier that the servicemen died while carrying out a combat training mission in the southwestern Mangystau region, with the incident occurring following a “sudden deterioration in weather conditions and intensifying winds.”

“According to preliminary information, 19 servicemen were swept out to sea,” the statement said, noting that three servicemen were rescued and that search and rescue efforts for the remaining personnel are underway.

A commission led by Defense Minister Dauren Kosanov was urgently deployed to the site to establish the circumstances behind the incident and coordinate search and rescue efforts, it added.

“Further information regarding the progress of the search operation and the condition of the servicemen will be released as data is received and verified,” it added.

Kazakh President Kassym-Jomart Tokayev declared Sept. 25 the day of mourning in the country to honor the memory of the servicemen killed.