Journalists waiting for a major announcement by Deputy Attorney General Rod J. Rosenstein Friday suddenly quieted.

“What I’m about to tell you is off the record,” said NBC News Justice Correspondent Pete Williams, not realizing that the Department of Justice video stream was live. So minutes before Rosenstein could announce the news, Williams told the world the still-embargoed information: special counsel Robert S. Mueller III had filed new indictments charging 12 Russian intelligence officials with conspiring to hack the 2016 Democratic National Convention computers.

A news embargo is a source’s request to refrain from publishing information until a certain time. 

Social media was immediately abuzz.

“Pete Williams on hotmic: 12 Russian hackers indicted for DNC hack,” tweeted Justin Miller, national editor of The Daily Beast.

“Oh,” Williams said. “I can’t talk more about it until Rosenstein comes out.”

Soon thereafter, DOJ spokesman Devin O’Malley addressed the journalists and lifted the already-broken embargo.

By then, though, the secret was out.

Neither Williams nor a DOJ representative immediately responded to a request for comment.