Washington (CNN) Two members of Congress who represent Florida are demanding a classified briefing from the Justice Department for the state's congressional delegation regarding the claim that Russia successfully hacked into at least one Florida county network before the 2016 election.

"We are determined to learn as much as we can about what transpired so that, as lawmakers, we can take appropriate steps to prevent such intrusions from reoccurring in the future," US Reps. Stephanie Murphy, a Democrat, and Michael Waltz, a Republican, wrote in a letter dated Thursday to Attorney General William Barr and FBI Director Christopher Wray.

Murphy and Waltz said the special counsel Robert Mueller's report "raises a host of critically-important questions that require answers."

A redacted version of the Mueller report released last month stated that the Russian military intelligence agency, the GRU, sent spearphishing emails to over 120 email accounts used by Florida county officials. The spearphishing emails had a Word document attached that was "coded with malicious software that permitted the GRU to access the infected computer," according to the Mueller report.

"We understand the FBI believes that this operation enabled the GRU to gain access to the network of at least one Florida county government," Mueller wrote.

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