Saturday's game between the St. Louis Cardinals and Milwaukee Brewers has been postponed following additional positive tests among the Cardinals, according to ESPN and multiple reports.

At least four more members of the Cardinals have tested positive for COVID-19, according to ESPN and multiple reports.

It is not known whether the new positive tests came from Cardinals players. Baseball reporter Craig Mish first reported on the new cases.

Major League Baseball commissioner Rob Manfred had told MLB Players Association executive director Tony Clark on Friday that if the sport doesn't do a better job of managing the coronavirus, it could shut down for the season, sources familiar with the conversation told ESPN's Jeff Passan. In text conversations with teammates Friday, MLBPA player representatives also warned about the threat to the season, according to Passan.

Friday's series opener was postponed after two Cardinals players tested positive for the coronavirus. The game was moved to be part of a doubleheader Sunday -- the first set of seven-inning games under an agreement announced by Major League Baseball on Friday.

After learning of the first two positive cases Thursday night, the Cardinals said that they instructed all players and staff to self-isolate in their hotel rooms in Milwaukee until further notice.

The Cardinals' positives represented the first positive tests for baseball outside of the East Coast since the regular season started last week.