Major League Baseball will suspend operations, including spring training and the first two weeks of the regular season, for the next four weeks, in response to the spread of coronavirus, the league announced Thursday. The MLB regular season was originally set to start March 26, but Opening Day will now be played no earlier than April 9. MLB is the fourth major American pro sports league to suspend its season due to the outbreak of COVID-19, joining the NBA, NHL and MLS.

The decision came after the league's owners discussed plans on a conference call Thursday afternoon. MLB ceased operations at 4 p.m. ET on Thursday, but spring training games were played as scheduled in Florida earlier in the day with fans in attendance.

Minor League Baseball also announced the start of its season would be delayed, and MLB said that qualifying for the World Baseball Classic was postponed indefinitely.

Here is the league's full statement on its decision:

Following a call with the 30 Clubs, and after consultation with the Major League Baseball Players Association, Commissioner Robert D. Manfred, Jr. today announced that MLB has decided to suspend Spring Training games and to delay the start of the 2020 regular season by at least two weeks due to the national emergency created by the coronavirus pandemic. This action is being taken in the interests of the safety and well-being of our players, Clubs and our millions of loyal fans. MLB will continue to evaluate ongoing events leading up to the start of the season. Guidance related to daily operations and workouts will be relayed to Clubs in the coming days. As of 4:00 p.m. (ET) today, forthcoming Spring Training games have been cancelled, and 2020 World Baseball Classic Qualifier games in Tucson, Arizona have been postponed indefinitely. MLB and the Clubs have been preparing a variety of contingency plans regarding the 2020 regular season schedule. MLB will announce the effects on the schedule at an appropriate time and will remain flexible as events warrant, with the hope of resuming normal operations as soon as possible. Nothing is more important to us than the health and safety of our players, employees and fans. MLB will continue to undertake the precautions and best practices recommended by public health experts. We send our best wishes to all individuals and communities that have been impacted by coronavirus.

Here are five more things to know about MLB's decision.

1. Spring training suspended

Both the Grapefruit and Cactus League schedules were suspended beginning Thursday afternoon. MLB's release also refers to the schedules as being "canceled," though it would stand to reason that some kind of ramp-up period will be in place ahead of the regular season. It's too early in the process to know exactly how that process would work.

2. Season will begin late

The current hope on MLB's side is that the league will miss out on only the first two weeks of the season, which was set to begin on March 26. It's unclear if that's a realistic desire, and it's at least possible that more time will be required before normal business can be resumed.

It's also unclear how MLB would approach the season, regardless of when it comes. Presumably all options will be on the table, including shortening the season, tacking games on afterward, or even playing doubleheaders to make up for lost time. Teams would have about 150 games on their regular season schedules if play started April 9 and no games were made up.

3. Suspension occurred during games

One of the oddest aspects of MLB's announcement is that it came while teams were playing games in Florida. Despite the NBA making its call last night, MLB did not cancel Thursday afternoon Grapefruit League contests that started in the early afternoon. As for the Cactus League, most of those games had already been canceled due to rain.

4. MLB was last league to act

Baseball was the last of the in-season major professional sports leagues to act in response to COVID-19.

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The National Basketball Association was the first of the four major leagues, suspending its season on Wednesday night after Utah Jazz center Rudy Gobert tested positive for the coronavirus prior to the start of a game against the Oklahoma City Thunder. MLS announced a suspension of its season Thursday morning and the NHL followed suit on Thursday afternoon, just before MLB's ruling came down.

5. What is coronavirus?

Coronaviruses are a large group of viruses that can cause illnesses as minor as a cold, or as serious as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS), according to the World Health Organization. The virus can cause symptoms including fever, cough and shortness of breath, according to the U.S. Centers for Disease Control and Prevention. But while some patients only show mild symptoms and recover, others have developed life-threatening complications, such as pneumonia, CBS News reports.

CBS News has the latest updates about the virus, which has affected various sports globally and in the United States. Here at CBS Sports we have a running updates on how sports leagues are responding to coronavirus.