A cyber attack thought to have originated outside the U.S. targeted several major U.S. newspapers, prompting printing and delivery disruptions this weekend, according to Reuters. Newspapers impacted by the cyber strike include the Chicago Tribune and Baltimore Sun, both owned by Tribune Publishing Co, as well as the Los Angeles Times. These newspapers “share a production platform” in Los Angeles, The Times said. An official for Tribune Publishing said the company first found the malware on Friday, per Reuters. The Wall Street Journal and New York Times’s West Coast editions were also impacted, as they are also printed on the joint platform. The vast majority of San Diego Union-Tribune subscribers didn’t receive a newspaper on Sunday because the virus infected its business systems. A Tribune spokeswoman said in a statement that “There is no evidence that customer credit card information or personally identifiable information has been compromised,” Reuters notes.