"The NBA is suspending game play following the conclusion of tonight's schedule of games until further notice,'' the league said in a statement issued shortly after 9:30 p.m. ET.
"The NBA will use this hiatus to determine next steps for moving forward in regard to the coronavirus pandemic.''
The player is the Jazz's Rudy Gobert, sources told ESPN's Adrian Wojnarowski. That led to Utah's game at Oklahoma City being postponed just before tipoff.
A source told ESPN's Royce Young that Gobert was never at Chesapeake Energy Arena on Wednesday, but he was in Oklahoma City and was set to play if he'd tested negative for coronavirus.
Players were on the floor for warm-ups when they were told to return to their locker rooms. About 30 minutes later, fans were told the game was postponed "due to unforeseen circumstances."
Jazz and Thunder players are currently quarantined at the arena, league sources tell ESPN.
Players from teams the Jazz have played within last 10 days are being told to self quarantine, sources tell ESPN's Brian Windhorst. Those teams are the Cleveland Cavaliers, New York Knicks, Boston Celtics, Detroit Pistons and the Toronto Raptors.
Charlotte Hornets coach James Borrego, speaking before his team played at Miami on Wednesday -- where news of the shutdown broke during the fourth quarter -- said "these are scary times.''