Jason Rezaian, Saeed Abedini and Amir Hekmati, who are Iranian-American, flew from Tehran on Sunday after their release. Fellow prisoner Matthew Trevithick had already left Iran on Saturday. The final prisoner, Nosratollah Khosravi-Roodsari has also been released but was not on the plane.
"We can confirm that our detained U.S. citizens have been released and that those who wished to depart Iran have left," said a US official.
As its part of the deal, the US released seven Iranians, six of whom also held American citizenship, held in US prisons. In addition, 14 Iranians who the US had placed on an Interpol wanted list have had their names removed.
In July Iran agreed on a Joint Comprehensive Plan of Action (JCPOA) in relation to its nuclear program with the IAEA and six countries (China, France, Germany, Russia, the United Kingdom, the United States) plus the European Union in July 2015.
Under the terms of the deal, Iran agreed to limit its nuclear capabilities and submit to IAEA monitoring of its facilities in return for the lifting of economic and financial sanctions.