Bartz said in a memo to employees that she was fired over the phone, one of the sources said.
"I am very sad to tell you that I've just been fired over the phone by Yahoo's Chairman of the Board," she said in a terse email. "It has been my pleasure to work with all of you and I wish you only the best going forward."
The company's board named Chief Financial Officer Tim Morse as the interim CEO, the other source said.
(Reporting by Alexei Oreskovic; editing by Carol Bishopric)