Facts are often the first casualty when news breaks. The confusion and speed of onrushing events can crimp the accuracy of the who, what and when of a story.

But some news reports of a shooting at Washington’s Navy Yard on Thursday didn’t just blow the details. In a few cases, reporters got the whole story wrong.

“Multiple sources confirm there was a shooting at Navy Yard just after 7:30 a.m.,” Washington’s Fox station, WTTG (Channel 5), tweeted as reporters and law enforcement personnel converged on the scene.

In fact, there was no shooting — only reports of one, apparently based on a single phone call to D.C. police from someone within the complex. But for brief and tense moments, some media outlets reported otherwise, summoning up grim memories of the September 2013 shootings that left 12 Navy Yard workers dead.

Germanie Alexander and BreAnna Holmes were on their way to work on Thursday, July 2 when they were stopped by police and told to evacuate the scene because of a report of possible gun shots fired inside the Washington Navy Yard. (McKenna Ewen and Whitney Leaming/The Washington Post)

WTTG, for one, didn’t stop with its initial, mistaken report.

A few minutes after its first alert, the station relayed information it said came from one of its reporters, Paul Wagner: “2 law enforcement sources say TWO armed men seen inside #NavyYard bldg 197, 1 possible victim,” with a link to a story on the station’s Web page.

In fact, there were no armed men, other than police, and no victim inside Building 197, the site of the 2013 shooting.

The station noted the grim locale a few minutes later by retweeting reporter Melanie Alnwick’s tweet, which seemed to confirm its earlier, erroneous report: “Eerie to see helicopters over #NavyYard once again. Source confirms shooting to @fox5newsdc.”

WTTG anchor Steve Chenevey played it both ways: “NAVY saying it can’t confirm shooting at #NavyYard but our assignment manager has multiple sources confirming shooting inside building 197.”

Meanwhile, other reporters “confirmed” the idea that a shooting had taken place rather than a mere report of a possible shooting. WUSA (Channel 9), the Washington CBS affiliate, retweeted reporter Nikki Burdine’s breaking tweet before 8 a.m: “Police source tells me Navy security reporting 2 shooters.” The station also had its own tweet to the same effect: “Navy security sources say police are looking for 2 men at #NavyYard.”

Soon, there was more “confirmation” of the supposed confirmation, but this time from an actual named source.

D.C. Mayor Muriel E. Bowser spoke at a news conference from Navy Yard Thursday. She praised security officials' "clear, convincing response" to the report of a shooting. (AP)

At 8:23 a.m., Fox News correspondent James Rosen called “Fox and Friends” live on the air — from Vienna, Austria, where he is traveling with Secretary of State John F. Kerry — to report on a bulletin issued to State Department employees moments before. Rosen said the bulletin had confirmed the presence of an active shooter at the Navy Yard. “So this represents confirmation from inside the Department of Defense, distributed to the State Department, of this active shooter at the Navy Yard,” Rosen said

Fox News quickly put up graphics reading, “Active Shooter Confirmed in DC Navy Yard” and “Shots Confirmed, Gunfire Reported Inside the Building.”

But almost as quickly as the erroneous reports streaked across social media and TV, clarity began to set in.

By 8:09, WTTG was starting to back away from its dire framing of events: “#NavyYard update via @Fox5Wagner: Initial rpt of armed men came from security guard in bldg looking at security cameras,” it said.

By around 8:30, police and Navy officials were telling reporters there was no evidence of a shooting, or of shooters and victims. The media consensus began to reflect the false alarm.

WTTG did not return calls for comment. Fox News said that its reporting was accurate but that the government bulletin it reported on was not.

At WUSA, station manager and news director Bill Lord said the station’s reporting was for the most part fast, accurate and restrained, generally stressing the uncertainty surrounding the situation.

He acknowledged, however, that the report about the existence of “two shooters” was “a poor choice of words. . . . I thought we were pretty careful to describe things as a possible shooting, but one may have slipped past us.”

Lord noted that large, breaking news events have always been complicated to cover live, given that authorities are still trying to figure out what’s going on and few people have a definitive picture.

What’s more, the ubiquity and instantaneousness of social media can spread mistakes faster than ever.

“We’re always dealing with a lack of complete information,” said Lord, who directed WUSA’s live coverage from the station’s control room Thursday. “Our job is to point out where we lack information rather than fill in the blanks ourselves. These things are never flawless.”

Correction: A previous version of this article incorrectly stated that the reports of a shooter at Navy Yard occurred on Friday. The incident took place on Thursday, July 2. It also stated that Fox News reporter James Rosen referenced a bulletin issued by the National Military Command Center. Rosen’s report mentioned two bulletins, both released by the State Department; one of those made reference to the NMCC, but it did not originate there.