WASHINGTON — One reason America's employers are having trouble filling jobs was starkly illustrated in a report Tuesday: Americans are quitting in droves. 

The Labor Department said that quits jumped to 4.3 million in August, the highest on records dating back to December 2000, and up from 4 million in July. Hiring also slowed in August, the report showed, and the number of jobs available fell to 10.4 million, from a record high of 11.1 million the previous month. 

The data strongly suggests that the delta variant wreaked havoc on the job market in August. As COVID-19 cases surged, quits jumped in restaurants and hotels and rose in other public-facing jobs, such as retail and education. 

Quits also rose the most in the South and Midwest, the government said, the two regions with the worst COVID outbreaks in August. 

When workers quit, it is typically seen as a good sign for the job market, because people typically leave jobs when they already have other positions or are confident they can find one. The large increase in August does include some goods news: It likely reflects the fact that with employers desperate for workers and raising wages, many workers feel they can get better pay elsewhere. 

But the fact that the increase in quits was heavily concentrated in sectors that involve close contact with the public is a sign that fear of COVID also played a large role. Many people may have quit even without other jobs to take. 

Hiring in September was weak for a second straight month, the government said Friday, with only 194,000 jobs added, though the unemployment rate fell to 4.8% from 5.2%. 

Tuesday's report, known as the Job Openings and Labor Turnover survey, or JOLTS, provides a more detailed picture of the job market. The hiring reported on Friday is a net total, after job gains and quits, retirements and layoffs are taken into account. Tuesday's report includes the raw figures, and showed that total hiring in August fell sharply, to 6.3 million from 6.8 million in July.