U.S. retail sales tumbled 16.4% from March to April as business shutdowns caused by the coronavirus outbreak kept shoppers away, threatened stores across the country and weighed down a sinking economy.

The Commerce Department’s report Friday on retail purchases showed a sector that has collapsed so quickly that sales over the past 12 months are down a crippling 21.6%.

The sharpest drops from March to April were at clothiers, electronics stores, furniture stores and restaurants. A long-standing migration of consumers toward online purchases is accelerating, with that segment posting a 8.4% monthly gain. Measured year over year, online sales surged 21.6%.

For a retail sector already reeling from the migration of consumers to online shopping and to app-based delivery services, a back-to-back free-fall in spending poses a grave risk. Department stores like Neiman Marcus and J.Crew have filed for bankruptcy protection. Hotels, restaurants and auto dealerships are in danger.

U.S. retail sales likely plummeted last month as the coronavirus paralyzed the economy, keeping away millions of shoppers and threatened the future of stores across the country.

The Commerce Department is expected to report Friday that retail purchases plunged 11.4% from March to April, according to economists surveyed by the data provider FactSet. That would be the steepest month-to-month fall since the government began keeping such records in 1992. And it would come on top of an 8.4% drop in March.

For a retail sector already reeling from the migration of consumers to online shopping and to app-based delivery services, a back-to-back free-fall in spending poses a grave risk. Department stores like Neiman Marcus and J.Crew have filed for bankruptcy protection. Hotels, restaurants and auto dealerships are in danger.

An April analysis by a group of academic economists found that a one-month closure could wipe out 31% of non-grocer retailers. A four-month closure could force 65% to close.