ATHENS, Greece (AP) — Two Turkish men have been arrested on suspicion of involvement in the fatal gangland shooting of six other Turks in Greece last month, Greek authorities said Wednesday.

Police said the six men killed in a Sept. 11 car ambush outside Athens were believed to have been members of an international crime group and had made a brief stop in Greece en route to Turkey.

Mass shootings of that kind are practically unheard of in Greece, and authorities had from the outset suspected a connection with foreign-based criminal organizations.

A police statement said one of the two detained suspects had made arrangements for the victims’ stay in Greece and travel plans to Turkey but allegedly led them into the fatal ambush in the seaside town of Artemida.

The six were attacked in their car as they drove to the Athens airport, and police said the killers finished them off with shots to the head fired at closed range.

Artemida is about 20 kilometers (12 miles) east of Athens and close to the airport.

One suspect, a 32-year-old man, was arrested at the airport hours after the shootings before he could board a flight to an eastern Aegean Sea island close to the Turkish coast. On Tuesday, police said, they detained a 28-year-old man in Athens.

The arrests followed cooperation with Greece’s secret service and counter-terrorism squad, police said, and exchanges of information with authorities from other countries.