INDIANAPOLIS — For the first time in 82 years, the country will spend a March absent one of the more animating links of its fabric. The NCAA, citing mounting concerns over the spread of the global coronavirus pandemic, canceled its men’s and women’s basketball tournaments Thursday afternoon.

The NCAA also canceled all other winter and spring championships.

“This decision is based on the evolving COVID-19 public health threat, our ability to ensure the events do not contribute to the spread of the pandemic, and the impracticality of hosting such events at any time during the academic year given ongoing decisions by other entities,” the NCAA said in its statement.

The spectacle known as March Madness, which was scheduled to begin next week, had been held every year since 1939 for men’s college teams and 1982 for women’s teams.

The NCAA made the unprecedented decision at the end of a dizzying day of cancellations across college basketball and the sports world. A riptide of coronavirus-related decisions began in late morning when a slew of Division I conferences canceled their basketball tournaments minutes apart, continued in early afternoon as the Big East in New York followed after one half of play and persisted across the day as schools nationwide announced the suspension of all their athletic events and travel.

“I’m going to speak from the heart a little bit here: This has been the most extraordinary stretch of days I’ve ever had or seen in my 30-plus years of working in the sports business,” said Big East Commissioner Val Ackerman, a former basketball player at Virginia, who soon added, “My prediction is if things escalate in this country, as we’ve seen in other parts of the world, I suspect it’s going to be very difficult for them to hold on to the NCAA tournament as planned.”

Reaction tore through coaches and the rosters. Gonzaga Coach Mark Few, whose team figured to have a No. 1 seed in the men’s tournament, heard the news while on air with ESPN’s Rece Davis and expressed disappointment that a postponement apparently couldn’t work. Ron Harper Jr., the Rutgers sophomore forward whose program was headed for its first berth since 1991, tweeted “#MarchSadness” and “It wasn’t supposed to go down like this.”

Kansas Coach Bill Self, who figured to have the No. 1 overall seed, said in a statement, “While we are disappointed for the players, it was the right and necessary thing to do.” Michigan State Coach Tom Izzo referred to beloved senior Cassius Winston and called his team meeting “a tear-jerking moment.”

Stars tweeted. Sophomore guard Tre Jones of Duke: “Doesn’t seem real, still.” Junior forward Jordan Nwora of Louisville: “This is tough for real.” Senior guard Myles Powell of Seton Hall: “Dear Seton Hall, I love you.”

Players for the top-ranked women’s team, South Carolina, tweeted, “This is so unbelievable” (Brea Beal), and, “So heartbroken for our seniors” (Destiny Littleton), and, “Unsettling and devastating but the absolute best decision for all” (Coach Dawn Staley).

Geno Auriemma, coach of the Connecticut women’s team, told ESPN earlier in the day, “The minute I read that one of the [NBA] players had tested positive” — a reference to Rudy Gobert — “I thought that was the beginning of the end.”

Hofstra men’s basketball, which had booked passage to a first NCAA tournament since 2001, tweeted a teary emoji.

By that point, 22 conferences canceled basketball tournaments — men’s, women’s or both. Before they did, an odd array of scenes played out at venues.

The Big East played one half of its first quarterfinal, between Creighton and St. John’s, at Madison Square Garden in New York before ceasing. Each participating Big East school was initially allowed 200 tickets for friends and family to attend Thursday, and attendees were instructed to sit on one side of the arena, with the other half already sanitized. Although the Big East sold separate tickets for its day and night sessions Thursday, attendees had been told they were free to stay at the arena for the later games, set to begin at 7 p.m.

Awkwardness cloaked venues such as the Big Ten and the ACC. Shortly after Michigan and then Rutgers players had taken the court at Bankers Life Fieldhouse here to warm up for their noontime game at the Big Ten tournament, the word came and prompted them to exit the court for their locker rooms and for good.

Before the ACC tournament was canceled, the Florida State and Clemson bands played at that event’s site, the Greensboro (N.C.) Coliseum, in advance of a game scheduled to go on without fans in the stands, as had been previously decreed Wednesday. ESPN’s Jay Bilas later reported that the contestants for the second game, Duke and N.C. State, did not intend to play as scheduled.

In downtown Indianapolis, fans here and there loaded up cars to depart, including one group wearing Michigan State gear. They would depart a tournament that held only two games, both on Wednesday night. By Thursday morning, the day after the Big Ten said the remainder of the event would be held without fans, hotels once primed for hubbub became ghostly. The sidewalks outside Bankers Life Fieldhouse were empty around 10 a.m., a group of police officers standing outside beneath a promotional sign reading, “March Is On.”

Inside that arena, where one electronic sign advises it’s 336 days until the home of the Indiana Pacers hosts the NBA All-Star Weekend, the late morning went by at a hushed court with only a row of reporters and various team and conference officials milling around. Then the Michigan team entered the court, and in a feat of wit, sophomore Brandon Johns Jr. and junior Isaiah Livers raised their arms toward the seats as if playing to the nonexistent cheering.

The team began warming up, and then the Rutgers team emerged. Within minutes, their exercise stopped, a small buzz went through the arena, and they all exited the court.

The Maryland Terrapins’ flight to Indianapolis was scheduled to take off at 3:15 p.m., with the team originally scheduled to open play Friday evening in the tournament quarterfinals.

Anthony Cowan Jr.’s father said his son, the Terps’ senior point guard, felt dejected and confused upon hearing the news that the Big Ten tournament had been scuttled. “We’re not sure what happens next,” said the elder Anthony Cowan, who had a flight to Indianapolis scheduled for Friday at 6 a.m. The father added that he understood the importance of prioritizing the health of those involved.

Speaking at a news conference in Indianapolis, Big Ten Commissioner Kevin Warren, who began his job in June, said, “I’ve just found over my career [in sports and law], the more complicated decisions are, the answer is much more simple, and this is just, ‘What is the right thing to do?’ ” He said, “I think the biggest thing was the uncertainty. This is one of those situations that a lot of people were telling me, ‘I don’t know.’ ”

About the change in course from Wednesday, he said, “I don’t think anything changed. Quite naturally, this is something that I’ve been evaluating over the last six weeks … I spent a lot of time thinking through this, meditating on it and really this morning praying over what is best.”

About the brief appearance of the Michigan and Rutgers players, he said, “I had to make sure that I was comfortable, that I had spoken to the appropriate people” — meaning chancellors, presidents and athletic directors.

Warren said the strange events of late Wednesday night had been “one piece of the decision-making process” but not a deciding one. Just after Indiana and Nebraska finished the two-game evening, Nebraska Coach Fred Hoiberg wound up examined in a hospital while his team wound up quarantined for about 90 minutes in its locker room. Hoiberg had looked miserably ill during the game and had exited the court four minutes before the finish. He and Nebraska had released a statement saying he had been diagnosed with the flu, not the coronavirus.

“When I woke up this morning,” Warren said, “even more than I did yesterday, I just felt in my spirit that this was the right thing.”

ACC Commissioner John Swofford decided likewise roughly an hour after holding a news conference to announce games still would be played. The official announcement came less than 12 hours after the ACC had planned to conduct the rest of the tournament, beginning with Thursday’s quarterfinals, without fans at Greensboro Coliseum even as the NBA said it would be suspending its season.

The move marks the first time the ACC tournament has been canceled in its 67-year history.

Top-seeded Florida State, which finished in first place in the regular season, was presented the conference trophy in a surreal ceremony on the court only minutes before the first quarterfinal game was scheduled to tip-off.

“We believe it’s the right decision to make at this particular time,” Swofford said. “You could ask why was it not made sooner. It’s a fair question. The answer is that it’s an extraordinarily fluid situation with information coming to us that changes — I used to say by the week, then I said by the day, and now I say by the hour.

“Hopefully we’re doing the right thing in the context of this great country of ours and in the context of intercollegiate sports.”

At the Big East, Ackerman said the league did not consider canceling the game before it began, even as news of other conferences canceling their tournaments rolled in while Creighton and St. John's players warmed up. On Wednesday night, the Big East limited attendance to essential personnel and players’ family members.

“It was just our view — we didn’t feel like we needed a dramatic, pull-the-players-off-the-court-in-the-middle-of-the-game gesture,” she said in a news conference. “Folks were here, we just literally didn’t think that an extra 15, 20 minutes of game time was going to make that much of a difference. That said, we didn’t think it was appropriate to send the athletes back out on the floor during halftime. So it was a judgment call that we made.”

In deciding not to cancel the tournament Wednesday night, when the NBA suspended the remainder of its season, Ackerman said the Big East followed both New York City directives and guidance from the NCAA. Unlike other large cities, New York had not announced any directives or limitations related to large gatherings as of Thursday afternoon.

“We felt that with the information that we had at the time — I think the NBA decision was in part driven by a positive coronavirus test as well by an athlete, which we don’t have in the Big East,” Ackerman said. “So they were operating on a slightly different fact set …”

Ackerman said no Big East players have been tested for the coronavirus because none have exhibited any signs of sickness.

Wallace reported from New York. Gene Wang, in Greensboro, N.C., and Emily Giambalvo, in Washington, also contributed to this report.