ATHENS, Greece (AP) — A European Union border agency patrol boat carrying five people, including the Estonian ambassador to Greece, has sunk off Greece’s easternmost island, the Greek coast guard said Monday. Four injured people were airlifted to a hospital on the island of Rhodes.

The Frontex patrol boat sank off the tiny Greek island of Kastellorizo after capsizing, the coast guard said. It did not give a reason for the sinking. Four Estonians, including the ambassador, and one Greek Frontex liaison officer were on board at the time.

The five were rescued by a Greek coast guard boat and a passing sailboat and transported to Kastellorizo, from where four injured people were airlifted to Rhodes. The coast guard did not specify whether the ambassador was among the four.

Last July, a Frontex patrol boat operated by the Portuguese Maritime Police sank off the eastern Aegean island of Lesbos during a search and rescue operation involving a boat carrying migrants. There were no injuries reported from that incident.

Greece is one of the main routes into the European Union used by people fleeing conflict and poverty in Africa, the Middle East and Asia. Frontex has been deployed in Greece for years, with vessels and personnel working alongside Greece’s coast guard and border patrol guards.