The NBA is instructing its teams to close their training and practice facilities effective Friday and until further notice, ESPN reported Thursday.
The mandate, issued in a memo to all 30 teams, applies to both players and staff members, according to ESPN.
The NBA suspended play last week after Rudy Gobert of the Utah Jazz tested positive for coronavirus. In all, four teams have said at least one player or a member of the organization has had a positive test.
The league earlier said players and staff members were allowed in team buildings under certain conditions.
But now, the players can't use team facilities, nor can they work out at any non-team sites, meaning players must do their workouts at home. The teams can provide workout materials for home use, the memo said.
The league also is encouraging players to remain in their home markets and stay isolated, leaving their homes only when required to get groceries or medicine, ESPN reported.
In an interview with the network Wednesday night, Silver said he hopes the league will be able to conclude the 2019-20 season but will follow all guidelines from government health officials.
"I'm optimistic by nature and I want to believe that we'll be able to salvage at least some portion of this season," Silver said.
--Field Level Media