The publisher of the Wall Street Journal said Friday it believes it was hacked by Chinese intelligence.

The breach was discovered on January 20.

News Corp said data was stolen from journalists and other employees.

It is not known when hackers breached the network or how much data they stole.

The breach affected a limited number of email accounts and documents from News Corp headquarters, News Technology Services, Dow Jones, News UK and New York Post.

News Corp told employees in an email to staff that it believed the “threat activity is contained.”

Other newsrooms, including The New York Times have previously been hacked.

Journalists in Mexico, El Salvador and Qatar have also been hacked with spyware.

News Corp also owns HarperCollins, News Corp Australia and Storyful.

It does not appear employees at those companies were affected by the hack.