But the journalists never returned to the auto - and were instead detained at a police station on the outskirts of Yangon, also known as Rangoon. Very soon after that Wa Lone's phone appeared to have been switched off.
The Reuters president and editor-in-chief, Stephen Adler, said: "We are outraged by this blatant attack on press freedom. We call for authorities to release them immediately".
The Myanmar Embassy in Washington could not be immediately reached for comment.
Two reporters, including a correspondent from the Yangon bureau of the Reuters news service, were arrested on the northern outskirts of the commercial capital last night and will face charges under Myanmar's colonial-era Official Secrets Act, Frontier has learned.
The U.S. State Deparment also expressed concern, tweeting that "freedom of the press if the cornerstone of democracy".
They have been charged under a section of the Official Secrets Act that carries a maximum sentence of 14 years in prison. They got no official information until Wednesday evening.
Wa Lone has worked for Reuters about 18 months, covering a variety of stories, including the Rohingya refugee crisis in northern Rakhine state, while Kyaw Soe Oo has been with the news agency for about four months. He graduated from Yangon University, according to his LinkedIn page.
The two Yangon-based journalists, Wa Lone and Kyaw Soe Oo with Reuters News Agency, were arrested for possessing important and secret government documents with regard to Rakhine state and security forces, and intending to send them to a foreign news agency, a release of the police force was quoted as saying.
An estimated 646,000 Rohingya Muslims fled the region to neighboring Bangladesh during a recent brutal military crackdown which began on August 25 following deadly attacks by Muslim militants. Many among the predominantly Buddhist population, including Burmese officials, reject the label "Rohingya" and instead use "Bengalis" to emphasize that Rohingya Muslims migrated illegally to the country from Bangladesh.
Myanmar has been widely criticised over the army crackdown in Rakhine.
"For a democracy to succeed, journalists need to be able to do their jobs freely", officials said.
The US embassy in Myanmar said it was "deeply concerned" about the arrests and urged the government to allow access to the pair.
"Myanmar media's freedom will definitely deteriorate if these reporters are punished", Myint Kyaw said.
The senior Southeast Asia representative of the Committee to Protect Journalists, Shawn Crispin, called on Myanmar's government to "immediately, unconditionally release" the reporters.
Other journalists in Myanmar have been arrested in recent months. Two foreign journalists along with two of their Myanmar associates are now awaiting trial on new charges after already being sentenced to jail for illegally flying a drone over parliament. "This incident is one in a pattern of arrests meant to prevent journalists from reporting the truth on the ground".