Tuesday's Washington Capitals-Philadelphia Flyers game has been postponed because of COVID-19 issues on the Flyers, a source confirmed to ESPN.

The Flyers are now the fifth NHL team on pause. The Buffalo Sabres, Colorado Avalanche, Minnesota Wild and New Jersey Devils have all had games postponed this week thanks to clusters of COVID-19 cases.

Last week, the NHL enhanced its in-arena safety protocols, including enforcing more social distancing in locker rooms and removing glass behind benches for increased air circulation. The NHL also tried mandating that players arrive to the rink no less than one hour and 45 minutes before a game -- though the league softened its stance on that, because of significant player pushback.

The NHL has been testing players and staffers daily with PCR tests, but it has begun to layer in more rapid testing at arenas, especially on game days.