U.S. intelligence officials say "top-secret" emails Hillary Clinton kept on her private email server when she headed the State Department include the real names of CIA spies serving undercover overseas — a violation of federal law that has put the agents in harm's way, The Observer reports. And, The Observer's John Schindler writes, those emails also include the names of foreigners on the CIA payroll, possibly endangering their lives."At a minimum, valuable covers have been blown, careers have been ruined, and lives have been put at serious risk. Our spies' greatest concern now is what's still in Hillary's emails that investigators have yet to find," Schindler, a former National Security Agency analyst, says in his report.He also quotes a senior intelligence community official as saying the security breach is a "death sentence.""If we're lucky, only [foreign] agents, not our officers, will get killed because of this," the official says.The Observer report comes four days after the State Department said it was withholding 22 emails from Clinton's server because they contained "top-secret" information, although the agency gave no hint about what that classified information was.The FBI has been investigating Clinton's use of a private server to determine whether it is a criminal matter.The Observer calls the breach a clear violation of federal law, citing the Intelligence Identities Protection Act of 1982, voted into law following the murder of the CIA spy in Greece after his identity was disclosed in the media.CIA brass believe some or all or Clinton's emails, which were kept on her home server and were apparently unencrypted, were intercepted by foreign powers.Clinton insists she never sent or received e-mails that were marked classified from the home server and blames Republicans for stoking the controversy. She has also asked that the 22 emails being withheld by the State Department be released.Clinton, the Democratic presidential front-runner, said she doesn't believe Americans are concerned about the email firestorm."I can tell you that is not on the minds of the literally thousands of people that I've seen in the last few weeks. I'm glad it isn't," she told CNN.