The BNP Paribas Open tennis tournament, set to begin this week, has been called off after a case of the new coronavirus was confirmed in the Coachella Valley in Southern California.

The Riverside County Public Health Department declared a public health emergency Sunday for the desert cities 110 miles east of Los Angeles, including Indian Wells, where the ATP and WTA tours were to play the two-week tournament starting Wednesday.

Gov. Gavin Newsom has declared a state of emergency. California has reported 114 cases of the virus.

"There is too great a risk, at this time, to the public health of the Riverside County area in holding a large gathering of this size," Dr. David Agus, professor of medicine and biomedical engineering at the University of Southern California, said in a statement. "It is not in the public interest of fans, players and neighboring areas for this tournament to proceed. We all have to join together to protect the community from the coronavirus outbreak."

WTA Tour chief executive Steve Simon told The New York Times that playing the tournament without fans was under consideration but ultimately was rejected by officials.

"We were supportive of the concept," Simon told The Times. "But ultimately the tournament didn't feel it was in their best interest."

Simon also said in a statement that "it is too soon to speculate about what will happen to other tournaments that follow. We will continue to closely monitor the situation. Health and safety will always come first."

The event typically draws upward of 450,000 spectators. This year's field included Rafael Nadal, Novak Djokovic, Serena Williams, Naomi Osaka and Coco Gauff.

So sad to hear the news about the postponing of the @BNPPARIBASOPEN . I was so excited to make my debut in IW, but safety is always the no.1 priority. Stay safe ??❤️

— Coco Gauff (@CocoGauff) March 9, 2020

Tournament director Tommy Haas said organizers are prepared to play the event on different dates and will explore options.

The decision to postpone Indian Wells was based on the guidance of medical professionals, the Centers for Disease Control and state of California officials, tournament officials said.

Refunds for this year's event or a credit toward next year's tournament are being offered.

Riverside County health officials said the individual with the first case of locally acquired coronavirus is being treated at Eisenhower Health in nearby Rancho Mirage after testing positive. The person is not being identified because of confidentiality rules.

Heath officials are following up on people who might have been exposed, and an investigation is underway to find out how the person contracted the disease.

It's the second case recorded in Riverside County. A cruise ship passenger from Riverside County was recently diagnosed with COVID-19 and is recovering at a Northern California medical facility. That person hasn't returned home since leaving the Diamond Princess ship.

"We have always known this was a possibility,'' said Dr. Cameron Kaiser, Riverside County public health officer. "We have been planning for weeks and are prepared to take the necessary steps to protect the health of our local community."

A charity event featuring Nadal set for Tuesday at Indian Wells Tennis Garden has been canceled, tournament spokesman Matt Van Tuinen said.

Nadal was set to be joined by defending BNP Paribas Open champion Dominic Thiem, Daniil Medvedev, Matteo Berrettini, Stan Wawrinka, Milos Raonic and American Taylor Fritz for the Eisenhower Cup, a $150,000 winner-take-all event.

You probably all heard the news. Indian Wells cancelled. We are here and still deciding what's next. So sad for all that is happening around the world with this situation. Hopefully soon solutions from the authorities. Stay all well and safe.

— Rafa Nadal (@RafaelNadal) March 9, 2020

Earlier in the week, officials announced several measures to protect players, fans and staff at the tennis tournament. Ball kids were going to wear gloves and not touch the towels of players on the court. Organized player and fan interaction was going to be limited at the tournament, which is informally referred to as the fifth Grand Slam because of its popularity with players and fans, many of whom come from overseas. Besides ball kids, restaurant and food-supply workers were going to wear gloves, as were volunteers taking tickets at entrances. More than 250 hand-sanitizing stations were set up throughout the venue.

Other major sports and entertainment events in the desert are scheduled for next month.

The LPGA Tour is to play the first women's golf major of the year, the ANA Inspiration, on April 2-5 in Rancho Mirage.

The Coachella Valley Music and Arts Festival in nearby Indio is set for April 10-12 and April 17-19. It typically draws 250,000 people over two weekends. The Stagecoach Festival, featuring country music, is scheduled for April 24-26 at the same Indio venue.

The Associated Press contributed to this report.