The officials searched the pair's belongings and would not return their passports when asked, according to Quintal.
It is also unclear whether Tanzanian authorities have Quintal's cellphone, after a number of her social media profiles were deactivated on Wednesday evening.
The country's Immigration Department said it had arrested them because they violated their stated objective of visit to Tanzania. It is now abundantly clear to anyone who followed the latest developments that Tanzanian journalists work in a climate of fear of intimidation.
South Africa's Department of International Relations and Cooperation (Dirco) said the two journalists are back in their hotel.
The Department of worldwide relations and cooperation says South African journalist Angela Quintal and a colleague returned to their hotel in Dar es Salaam, Tanzania, in the early hours of this morning. "The High Commissioner and his Kenyan diplomats will continue to engage with Tanzanian authorities until the passports are returned and all the facts have been established around the arrest", Dirco said.More news: Scientists are now arguing about whether Oumuamua was sent by aliens
More news: Democrats get first House pick-up of midterms
More news: Dani Carvajal: Julen Lopetegui is the best coach I’ve ever had
Mtanda said Quintal and Mumo were free to stay on in Tanzania as long as they heeded the terms of their 90-day visa.
Tanzanian Immigration Department spokesperson Ali Mtanda said Angela Quintal and Muthoki Mumo were arrested for violating the terms of their visas by holding meetings with local journalists.
Immigration spokesperson Ally Mtanda told The Citizen that the department had arrested the two journalists and questioned them, saying, "they arrived in the country on October 31, 2018 through the Julius Nyerere International Airport (JNIA) in Dar es Salaam and they said the goal of their trip was normal visit".
Quintal and Mumo were then escorted from the hotel and have been taken to an unknown location.
CPJ Executive Director Joel Simon expressed gratitude and appreciation to journalists, media and press freedom organizations, and government officials who spoke out about Quintal and Mumo's detention. "The United States remains committed to the values of democracy, rule of law, freedom of expression, and prosperity in Tanzania".