MOSCOW (AP) — Ukraine's border guards service says one of its cutters exploded while on patrol off the shore of the strategic port city of Mariupol.
Two of the seven servicemen on board were injured and the status of the others has not been determined.
It wasn't immediately clear what caused the explosion Sunday afternoon.
Fighting between pro-Russian separatists and government forces near Mariupol has persisted for months, despite a cease-fire called in February and the subsequent reduction in overall hostilities in the east.
Mariupol is the major coastal city between mainland Russia and the Russia-annexed Crimean peninsula. Rebel seizure of the city could help establish a land bridge corridor connecting the two.