U.S. stock markets plummeted Monday morning amid fears that the coronavirus will continue to spread beyond China’s borders.

The Dow Jones Industrial Average plunged 900 points, or 3.1 percent, among its biggest one-day drops in recent years, while the S&P 500 Index dropped 100 points, or 3 percent percent, less than a week after reaching a record high.

The declines follow reports that countries beyond China are now struggling to contain the spread of the coronavirus. South Korea raised its alert level to the highest level as infections topped 830, while Italian officials worked to contain an outbreak of 220 cases and Iranian officials confirmed 61 cases.

The vast majority of the 78,000 cases of the virus are in China, where more than 2,400 people have died from the illness.

Steps to contain the virus have disrupted air travel and some businesses dependent on Chinese manufacturing, including supply chains for electronics.

Last week, a Goldman Sachs analysis warned that investors weren’t taking the coronavirus seriously enough, and that markets were due for a correction.

Some economists have predicted the virus will weaken growth in the near term, but also expect markets and the global economy to bounce back quickly when the spread of the virus is under control.