Iran moves toward freeing 5 American citizens who had been imprisoned, in rare deal

After months of quiet negotiations, Iran and the U.S. have reached an agreement that would see five American citizens considered to be unjustly detained released from custody and allowed to leave the country, ABC News has learned.

A lawyer representing one of the detainees tells ABC News that four of the five were released from Iran’s notorious Evin prison on Thursday and are currently under house arrest in the country.

The move sets the stage for what a person familiar with the negotiations described as “a process” that -- if all goes well -- could ultimately see the four freed along with a fifth U.S. national who was already under house arrest and, according to the White House, had previously been held in prison.

The detained U.S. citizens include Siamak Namazi, Emad Shargi and Morad Tahbaz, as well as two others who asked that their identity not be made public.

A spokesperson for the White House's National Security Council confirmed the Americans' release in a statement. "While this is an encouraging step, these U.S. citizens ... should have never been detained in the first place. We will continue to monitor their condition as closely as possible. Of course, we will not rest until they are all back home in the United States," the spokesperson, Adrienne Watson, said.