The season-opening series involving the Nationals and Mets was postponed Friday as the fallout from a COVID-19 outbreak one of the Nationals throw into question when Washington’s season would start.

At least three Nationals players have tested positive, and also the team supposes another player having an inconclusive result is positive too, leading to the postponement of the scheduled Opening Day game Thursday. Games on Saturday and Sunday were postponed as well and will be made up throughout the rest of the season, as the teams are scheduled to play 19 games from each other as National League East rivals.

The Mets will begin their season Monday at Philadelphia. When Washington plays will depend on the outcomes of contact tracing the group has undertaken in the aftermath of the outbreak.

Nationals staff and players have remained isolated in recent days, and the team hoped that its series starting Monday from the Atlanta Braves wouldn’t be imperiled too.

“For the most part, the whole team was — we place them — in lockdown and they are self-quarantining,” Nationals general manager Mike Rizzo said in a videoconference with reporters Thursday.

Rizzo said one of those players testing positive had a fever, although the others were not displaying COVID-19 symptoms.

The jointly negotiated protocol involving Major League Baseball and the MLB Players Association mandates a weeklong quarantine for someone deemed in close contact with individuals who have tested positive, and people determined to have COVID-19 have to isolate for at least 10 days.

Outbreaks on St. Louis and Miami last year interrupted the teams but ultimately didn’t violate them, as both made the postseason. The Nationals, who have playoff aspirations, will begin their season short-handed, as individuals who have tested positive will be set on the COVID-19 accident list.