The would-be terrorists, mostly Jordanian and Palestinian Arabs, were reportedly negotiating with a worker who held security clearance at the airport, located in the state of Hesse. The airport serves as the hub for Lufthansa Airlines and is one of the busiest in Europe.

The airport employee initially agreed to load a bag containing explosives into the belly of the plane, but refused at the end due to a disagreement over how much he would be paid.

The six, in addition to other unidentified conspirators, were backed by a “so far unknown” terror organization, according to a statement issued Monday by the Federal Prosecutor’s Office.

They were picked up last Friday by German authorities and held overnight for questioning. All were released, except one who was wanted on charges stemming from a different crime.

German law, like Israeli law, mandates that suspects cannot be held for longer than 48 hours unless sufficient evidence is shown to prove otherwise.

Aside from the statement by the federal prosecutors, government and airline authorities across the board refused comment on the case and were unwilling to provide any further information.