That number reflected a significant rise from last week's 211,000, which was unrevised from the initial estimate, according to the Labor Department. It was the highest number since Sept. 2, 2017.

Jobless claims rose to 281,000 last week, reflecting only the first indications of the impact the coronavirus will have on the U.S. employment picture.

The four-week moving average rose to 232,250, up 16,500 from a week ago and the highest level since Jan. 27, 2018. The previous week saw an upward revision to 215,750 from 214,000. The continuing claims level edged up to just over 1.7 million.

The department said the numbers were "clearly attributable to impacts from the COVID-19 virus. A number of states specifically cited COVID-19 related layoffs, while many states reported increased layoffs in service related industries broadly and in the accommodation and food services industries specifically, as well as in the transportation and warehousing industry, whether COVID-19 was identified directly or not."

Companies are just starting to announce coronavirus-related layoffs, so the real damage probably won't start showing through until next week's count, which will entail the period through this Saturday.

Ian Shepherdson from Pantheon Macroeconomics told CNBC earlier Thursday morning that next week's total could hit 2 million. He said in a subsequent note that the number even could hit 3 million.

"Next week's number ... will be an order of magnitude worse," Shepherdson wrote. "We hope that will be the single worst week, but we can't be sure."

Much of the layoffs so far have come from the hospitality industry, which have been slammed by a national effort of social distancing to keep the coronavirus spread at bay.

"There's no surprise here with the restaurant industry warning 5 to 7 million workers will lose their jobs in coming months," Chris Rupkey, chief financial economist at MUFG Union Bank, said in a note. "Today's jobless claims statistics provide the confirmation if it was needed that the economy has just fallen over the cliff and is turning down into a recession."

Marriott International said it will be laying off tens of thousands of employees. Compass Coffee, which is based in Washington, D.C. and competes with Starbuck's, has laid off 150 workers, or 80% of its staff. Danny Meyer's Union Square Hospitality Group said it would furlough 3,000 workers, also 80% of its workforce.

Get the market reaction here.