As the Phillies took batting practice Wednesday, word began to trickle over from the visiting clubhouse at Citizens Bank Park that the Washington Nationals were dealing with a COVID-19 disruption.

Less than an hour later, the game was postponed.

The Nationals have 12 positive tests, four of which were players, according to manager Dave Martinez, and the team will continue to undergo rapid testing and contact tracing to determine if the outbreak is more widespread.

But the Phillies and Nationals will attempt to play a single-admission doubleheader beginning at 12:05 p.m. Thursday, with the Phillies honoring only tickets for Thursday’s regularly scheduled game.

“We’re going to have to wait until we get these results back,” Martinez said in a videoconference after Major League Baseball announced the postponement. “Hopefully we’ll have them early [Thursday] morning. As I explained to our players, be ready to play [Thursday], expect to play [Thursday], and we’ll go from there.”

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One night earlier, star shortstop Trea Turner tested positive for COVID-19 and was removed after the first inning of Tuesday night’s 6-4 victory over the Phillies. Martinez said “nobody has gotten very sick” among the Nationals’ infected personnel and described any symptoms as “like a small head cold.”

The Nationals are among the teams that have reached the 85% vaccination rate of Tier 1 players and staff required to relax the COVID-19 protocols that were put in place by Major League Baseball when the season began. Of the dozen people who tested positive, Martinez said he’s aware of only one who is unvaccinated.

“I do believe the vaccinations have helped in a big way,” Martinez said. “I encourage people to get vaccinated. It does help. I’m seeing it firsthand.”

Martinez said the four infected players, including Turner, will have to test negative multiple times before being cleared to play. Some of the Nationals’ personnel was attempting to get permission to drive back to Washington rather than staying in Philadelphia until tests come back negative, according to Martinez.

“I really worry about the health and safety of everybody in our clubhouse and everybody else that could be affected, families,” Martinez said. “I wanted to get everybody out of here as soon as possible, get them back to the hotel rooms to get all of this sorted out.”

The Nationals will have to make several roster moves before Thursday’s games. The weather could complicate things, too. Rain is in the forecast for Thursday. The Nationals aren’t scheduled to return to Citizens Bank Park this season. The teams will play two more series, both in Washington (Aug. 2-5 and Aug. 31-Sept. 1).

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Several Nationals players, mostly pitchers, went through running, stretching, and long-tossing in the outfield while the Phillies took batting practice. Once the Phillies left the field, the ground crew disassembled the batting cage and other equipment used for batting practice. Zack Wheeler, the Phillies’ scheduled starter, played light catch in the outfield, a signal that the game wouldn’t be played.

Wheeler and Vince Velasquez are scheduled to start Thursday, although it’s not clear which game each will pitch.

The Phillies are among seven teams that hasn’t reached the 85% threshold. Third baseman Alec Bohm tested positive for COVID-19 on July 11, and three players, including star pitcher Aaron Nola, missed time after being identified as close contacts.

Fans who hold tickets for Wednesday’s game will receive a credit that can be used to purchase tickets to any remaining 2021 home game, the Phillies announced.