Ukrainian officials say 12 people are dead and another person is missing after an excursion boat overturned in the Black Sea near the major port city of Odessa.

The other 23 people who were aboard the boat were rescued, according to the Ukrainian Infrastructure Ministry.

The ministry said in a statement that the boat was en route to its berth about 40 kilometers (25 miles) southwest of Odessa when the capsizing occurred Saturday afternoon. The cause wasn't immediately determined.

A photo of the boat published by the Ukrainian news agency Unian shows it as a small motor vessel with awning-shaded viewing areas both fore and aft.