At least 21 hockey players on the Vancouver Canucks have tested positive for the coronavirus, the team said Wednesday in a statement. The massive outbreak, which has affected nearly all of the team’s players, is one of the largest that a professional sports team has faced during the pandemic.

The team’s outbreak first made news on March 31, when the Canucks postponed a game against the Calgary Flames after three positive COVID-19 tests in two days. The next day, the league postponed three more of the team’s games. In the past week, more and more players were added to the team’s COVID list. 

As of Wednesday, 25 members of the organization — 21 players and 4 staff members — have tested positive, according to a statement from the team written by the Canucks physician and an infectious disease specialist.

The doctors said the source infection was from a variant, but said further testing would be required to determine which variant it was. The team said an investigation by Vancouver Coastal Health and club officials suggests the source of the outbreak was a single person, who contracted the virus in a “public exposure location.” The team did not elaborate on where the believed source contracted the virus, or who that person is.

“This is a stark reminder of how quickly the virus can spread and its serious impact, even among healthy, young athletes,” the doctors said in a statement. 

The NHL has postponed 45 games this season due to health and safety protocols, according to CBS Sports. The team said all Canucks players and staff are currently in quarantine.