The Transportation Security Administration says nearly 100 U.S. Federal Air Marshals have contracted COVID-19, a sobering thought just as the airlines are making a push for how safe airplanes are ahead of the holiday travel season.

According to a report by Yahoo News , 98 marshals have tested positive for the coronavirus although it is unclear whether all cases were from flying. But many of the marshals who spoke with Yahoo News said they believe some of those infections are directly related to their time in airports and on flights.

In fact, last week several cases hit the Federal Air Marshals Dallas office and temporarily shuttered its field office in Philadelphia. And earlier this month, an air marshal based in Minneapolis died from COVID-19.

“The [Air Marshal Association] knows of one [federal air marshal] case at the start of the outbreak that is linked with certainty to a European flight,” said John Casaretti, president of the association, which represents about half the 3,000 air marshals.

Sonya Hightower LaBosco, president of the Air Marshal National Council, another organization that represents some air marshals, also said it has identified cases in which it believes its members contracted the virus from airplanes. “Absolutely, we know they got it flying,” she said.

Airlines have been touting reports that it is safe to fly again , so it remains unknown whether this news affects travel plans over the lucrative Thanksgiving-Christmas-New Year’s window.