There are many federal laws criminalizing the making of false statements, particularly when it leads to significant negative consequences. But when the spreading of false information could lead to mass panic and extensive waste of government resources, it's a particularly serious offense.

18 U.S.C. 1038 says, “(a) (1) In general. Whoever engages in any conduct with intent to convey false or misleading information under circumstances where such information may reasonably be believed and where such information indicates that an activity has taken, is taking, or will take place that would constitute a violation of…. shall be fined or imprisoned….”