The Washington Post's Tehran correspondent Jason Rezaian was detained on Tuesday evening, along with his wife and two others. (Zoeann Murphy/The Washington Post)

Three American citizens, including The Washington Post’s correspondent in Iran, appear to have been detained this week in Tehran, U.S. officials and the newspaper said Thursday.

Washington Post foreign editor Douglas Jehl said the newspaper has received “credible reports” that correspondent Jason Rezaian and his wife, Yeganeh Salehi, were detained Tuesday evening in Tehran. It is unclear who detained them or why.

“We are deeply troubled by this news and are concerned for the welfare of Jason, Yeganeh and two others said to have been detained with them,” Jehl said in a statement.

Jehl said that Rezaian, who has been The Post’s correspondent in Tehran since 2012, “is an experienced, knowledgeable reporter who deserves protection and whose work merits respect.”

Members of Rezaian’s family said they did not want to comment at this time.

Rezaian, 38, holds American and Iranian citizenship. Yeganeh, an Iranian citizen who has applied for U.S. permanent residency, works as a correspondent for the National, a newspaper based in the United Arab Emirates.

The other two American citizens detained with them work as freelance photojournalists. Officials have not yet identified them by name.

Marie Harf, a State Department spokeswoman, said that American officials are aware of reports of the detention of three U.S. citizens in Tehran this week.

“Our highest priority is the safety and welfare of U.S. citizens abroad,” she said. Harf said she had no additional information to disclose.

Hamid Babaei, a spokesman for the Iranian mission at the United Nations, said in an e-mail that Iranian diplomats are looking into the reported detentions.

“We will inform you as soon as we receive any news,” Babaei said.

The New York-based Committee to Protect Journalists issued a statement demanding the prompt release of the journalists.

“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,” said Sherif Mansour, the committee’s Middle East and North Africa program coordinator.

Because the United States and Iran don’t have formal diplomatic relations, negotiating the release of American citizens detained in Iran is complicated.

Journalists working for Western news organizations have struggled for years to get permission to cover news in Iran. Several have been detained in recent years for a variety of reasons.

Rezaian has been accredited by the government to work for The Post since 2012. He has been based in Iran as a journalist since 2008 and was previously accredited to work for other publications, including the San Francisco Chronicle.