Washington (CNN) FBI leaders expressed shock and sadness in internal messages in the immediate aftermath of James Comey's firing last spring, even as the White House attempted to portray a bureau in crisis, newly disclosed emails show.

"Our hearts may be heavy but we must continue to do what we do best," the head of the bureau's Office for Victims Assistance wrote to her department.

"I hope this is an instance of fake news," the top agent in the Detroit told his staff.

"We are not going to let this defeat us and like I said it will only make us stronger," the chief in the Knoxville field office said to her team. "Unexpected news such as this is hard to understand but I know you all know our Director stood for what is right and what is true!!!"

The emails, offering a window into the secretive law enforcement agency during an upheaval last May following President Donald Trump's decision to fire Comey, were revealed as part of a Freedom of Information Act lawsuit brought against the bureau by Ben Wittes, a friend of Comey's and the editor of the legal affairs blog Lawfare.