Watch Now: Reaction: Cardinals and Tigers Series Postponed (4:08)

The number of positive tests in the St. Louis Cardinals' COVID-19 outbreak grew to 13 on Monday, Major League Baseball announced. Seven positive tests were from players and six were from staff members. The league postponed St. Louis' four-game series against the Tigers that was scheduled to run Tuesday-Thursday after the latest round of testing.

On Tuesday the Cardinals announced the identities of six players who tested positive: Yadier Molina, Paul DeJong, Edmundo Sosa, Rangel Ravelo, Junior Fernandez, and Kodi Whitley. Each player had to give the team permission to announce their positive test.

"I am saddened to have tested positive for COVID-19, even after adhering to safety guidelines that were put in place," Molina said in a statement. "I will do everything within my power to return as soon as possible for Cardinals fans, the city of St. Louis and my teammates. As I recover, I request that you please respect my privacy and family in my absence from the team."   

The Cardinals did not play their weekend series against the Brewers after learning of multiple positive tests late Thursday night. They now will have seven games in a row postponed due to the outbreak. MLB is still planning on the Cardinals playing the Cubs on Friday.

Here's part of MLB's Monday statement:

The Club, which has been in quarantine since Thursday, will stay in Milwaukee and their personnel will continue to be tested daily.  The tentative plan is for the team to resume its regular schedule on Friday against the Chicago Cubs in St. Louis.

The Cardinals are the second MLB team dealing with an outbreak in a season that is not yet two weeks old. The Miami Marlins had four players test positive last weekend, and that number grew to 18 over the course of the week. The CDC estimates that COVID-19's incubation process can span from two to 14 days, with the median time being five days. New infections, then, are recorded on a lag.

Major League Baseball's season was believed to be endangered entering the weekend, based on comments commissioner Rob Manfred made to union head Tony Clark. ESPN's Jeff Passan suggested the season could be scrapped as soon as Monday. Another team-wide outbreak, or even the suspicion of one, within 10 days' time might leave Manfred with no other choice.

Another concern is whether the Cardinals spread the disease to the Minnesota Twins, their opponents and hosts earlier this week. The Twins have not had anyone test positive, and were on the field for a four-game series against Cleveland that started Thursday. If there is good news in that regard, it's that team-to-team transmission during a game seems unlikely.

Based on what's known about how COVID-19 transmits, the highest risk endeavors entail individuals spending a prolonged period at intimate distances amid a crowd in an enclosed or poorly ventilated setting. In other words, not outside on the field, where players are largely spaced out and are seldom near each other for lengthy periods. 

The Philadelphia Phillies, who played a series against the Marlins, have not yet had a player test positive, the team announced on Saturday.