Staffers at some of America's best-known newspapers are wondering whether their systems were the victim of a foreign cyberattack.
Several papers, including the Los Angeles Times and The San Diego Union-Tribune, suffered printing and distribution delays as a result of the incident.
Business and industry sectors
Business, economy and trade
Crime, law enforcement and corrections
Computer science and information technology
Software and applications
Some reporters chuckled at the irony of a digital bug interrupting printed papers. But there is also real concern about the effectiveness of the attack.
Tribune Publishing said "malware" was detected on its servers Friday. The Union-Tribune, which also called it a "virus," said most subscribers were left without a Saturday morning paper as a result.
The incident affected other newspapers in other ways. At The Baltimore Sun, for example, the usual comics and puzzles were not included in Saturday's print edition, the paper tweeted.
In Southern California, distribution of The New York Times and The Wall Street Journal was also delayed, because all of the papers rely on the same back-end printing presses.
The L.A. Times, citing a "source with knowledge of the situation," said Saturday that the cyberattack "appears to have originated from outside the United States."
A spokeswoman for Tribune Publishing said she could not confirm that.
And staffers at some of the affected papers said they haven't received much information from management about the extent of the cyberattack.
An internal memo from Tribune CEO Justin Dearborn on Saturday referenced "malware" and said "we are making progress with this issue."
Papers using Tribune software were affected. The L.A. Times and the Union-Tribune are no longer owned by Tribune, previously known as Tronc. But the papers continue to use some of Tribune's systems.
The virus "hobbled our ability to publish," Union-Tribune editor and publisher Jeff Light said in a Saturday morning letter to readers.
According to Dearborn's memo and the company's statement, workers had to create "workarounds" to get the Saturday editions printed.
"There is no evidence that customer credit card information or personally identifiable information has been compromised," Dearborn wrote.
But some important back-office systems were interrupted. When some L.A. Times readers called to inquire about their print edition, the customer service phone lines were on the fritz.
And staffers at two papers using Tribune software told CNN Business that the time card system for keeping track of working hours was offline for some time.
The websites of the affected papers were never impacted, however.
The South Florida Sun Sentinel's online story about the virus started off by saying: "We are still here."