Bloomberg News said it had taken “disciplinary action” against a number of its editorial staff after the outlet “prematurely” published news of the historic prisoner swap between Russia and the United States last week that it said could have endangered the safety of the Americans being released.

In an email to staff on Monday, editor-in-chief John Micklethwait wrote that a number of staff members had been disciplined, although the company did not say who, how many or what their punishment had been. At least one reporter on the story appears to have been fired in a rare case where a journalist was punished for a decision to publish a major news story that would likely have been reviewed by senior editors at the outlet.