Princess Cruises said on Thursday that it would suspend operations until at least May 11.

Two Princess ships were recently quarantined following positive coronavirus cases on board.

Shares of Carnival Corporation, Princess Cruises' parent company, plummeted more than 20% in early trading following the news.

Viking Cruises also canceled voyages this week as the coronavirus outbreak brings the cruise industry to its knees.

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Princess Cruises, a subsidiary of Carnival, said on Thursday that it would suspend sailing its 18 ships through at least May 11.

The cancellations came as the spread of the novel coronavirus — of which there are now more than 127,700 cases worldwide and more than 1,300 in the United States — hammers cruise companies, airlines, and more.

Two Princess Cruises ships were quarantined in recent weeks. After 21 people on board tested positive for the virus, the Grand Princess sat quarantined in the San Francisco Bay for days before docking in Oakland on Monday.

President Donald Trump on Wednesday announced a 30-day travel ban for foreign nationals arriving from most European countries, sending airline stocks plummeting.

In a press release, Princess Cruises said that passengers on a cruise set to end within five days would sail as expected and that voyages underway that are scheduled to conclude after next Tuesday would be ended at "the most convenient location."

The company also said it would provide ticket-holders cash refunds or vouchers for future cruises if their voyages are canceled.

Markets Insider Shares of Carnival Corporation fell more than 20% in early trading Thursday after the cancellations were announced. Across the board, markets in Europe and Asia plunged on Thursday, causing American trading to come to a halt.

On Wednesday, Viking Cruises also suspended operations as the coronavirus outbreak all but cripples the industry.

Earlier this month, analysts at JPMorgan said the outbreak's economic impact on cruise lines would likely be worse than on any of the other sectors the bank covers.

Jan Swartz, the president of Princess Cruises, said in the press release: "It is our intention to reassure our loyal guests, team members and global stakeholders of our commitment to the health, safety and well-being of all who sail with us, as well as those who do business with us, and the countries and communities we visit around the world."