After a week of silence, Iranian authorities on Tuesday released one of the four American journalists detained for a yet-to-be announced reason, a source close to the family of the released detainee told CNN.

Last Tuesday, The Washington Post's Tehran correspondent Jason Rezaian, his wife Yeganeh Salehi, and two photojournalists were arrested. Rezaian, Salehi, and one of the photojournalists remain in custody, the source said.

The release brings a sliver of hope to a murky situation, as Iranian officials have refused to explain why Rezaian and the others were detained. The only comment came from Gholam-Hossein Esmaili, director general of the Tehran Province Justice Department, who told the country's official IRNA news agency that Rezaian "has been detained for some questions," and that after investigations are conducted, "the judiciary will provide details on the issue."

Journalists immediately slammed the move. Thomas Erdbrink, Tehran bureau chief for The New York Times, tweeted his support for Rezaian:

Sherif Mansour, the Middle East and North Africa program coordinator for the Committee to Protect Journalists, released a statement saying:

"We call on Iranian authorities to immediately explain why Jason Rezaian, Yeganeh Salehi, and two other journalists have been detained, and we call for their immediate release.

Iran has a dismal record with regard to its treatment of imprisoned journalists. We hold the Iranian government responsible for the safety of these four.

On Monday, The Washington Post published an editorial expressing frustration at the little news on Rezaian and his colleagues, as well as explaining why their release is necessary, as Rezaian's health could be compromised in custody. "What is known is that Mr. Rezaian, 38, suffers from high blood pressure and probably does not have access to his regular medication," the paper's editorial board wrote. "In addition to endangering his health, his arrest silences a reporter who was dedicated to fairly explaining Iran to Washington readers."

In a video released by The Washington Post, Rezaian's mother pleaded for her son and colleagues' freedom:

"I love my son and daughter and I am proud of their commitment to journalism," she said. "I humbly ask those who continue to detain my son and daughter to please release them."