KANSAS CITY — Ten football fans who attended the Kansas City Chiefs game together last week have been told to quarantine after one of them tested positive for a coronavirus infection.

Kansas City health officials said Thursday that the person tested positive a day after the group watched the game from their box in Arrowhead Stadium’s lower level.

The Chiefs say in a statement that the people involved were wearing masks when they entered the stadium as required. The team says its contact tracing system allowed it to identify those sitting with the infected person, service staff who might have had contact with the person, and others near the person when he or she entered the stadium.

The Chiefs opened the NFL season last week against the Houston Texans with only 22% capacity — about 17,000 fans — at Arrowhead. Fans were required to wear masks and social distance and other safety precautions were in place.