The NBA suspended all games starting Thursday after a player for the Utah Jazz preliminarily tested positive for COVID-19, the disease caused by the new coronavirus.
The league said play would be suspended until further notice.
The test result was reported shortly before tipoff of Wednesday night's game between the Utah Jazz and Oklahoma City Thunder in Oklahoma City, according to a statement from the NBA. The game was canceled immediately.
The affected player was not in the arena at the time of cancellation. The NBA also announced that it would use the hiatus to determine its next steps.
A game between the Sacramento Kings and the New Orleans Pelicans in New Orleans was also suspended because one of the referees at the game had worked a Jazz game earlier in the week, according to NBC Sports.
Wednesday night's other games were allowed to go ahead.
The move by the NBA is the biggest in the U.S. to date in response to concerns about the spreading coronavirus. Earlier Wednesday, the NCAA said it would restrict attendance at its coming Division I men's and women's basketball tournaments to staff and family.
Reporters at the Jazz-Thunder game tweeted that the entire arena was emptied and that both teams were still in their locker rooms while the Jazz bench area was cleaned.
The suspension follows an announcement by the Golden State Warriors that they would play a game Thursday night without fans. The Warriors said they "completely support" the league's move to suspend games.
"As we noted earlier today, with the escalating situation surrounding COVID-19, we find ourselves in a rapidly-changing environment by the day, if not the hour," the team said in a statement.
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The NBA playoffs are set to start in mid-April. Most teams have fewer than 20 games left in the regular season.
The NHL said in a statement that it is "aware of the NBA's decision tonight to indefinitely suspend its season due to a player testing positive for the coronavirus."
"The NHL is continuing to consult with medical experts and is evaluating the options. We expect to have a further update tomorrow," the league said.
The NHL is scheduled to start its postseason April 4.
NBA players reacted with a mix of shock and concern — and some perspective. Many referenced that 2020 thus far has been tumultuous.
Los Angeles Lakers star LeBron James tweeted that "it’s been a rough 3 months. God bless and stay safe."
Others sought to strike a note of optimism that the league will resume play at some point this season.
"TO BE CONTINUED.!!!" tweeted Miami Heat player Jae Crowder.
The suspension of the league also has particularly important consequences for one player — Vince Carter.
Carter, currently a player for the Atlanta Hawks, is in his 22nd and final NBA season. One of the most exciting players of the 2000s — earning the nicknames "Vinsanity" and "half man, half amazing" — Carter is also one of the most well-liked players in the league.
After the Hawks' Wednesday night game, Carter became emotional as he spoke to the press after what could end up being his final game. He hit a three-point shot in the final seconds of the game.
"Basketball's been good to me," he said. "If this is it, it's all good. At least I made my last basket."