L.A. County’s unemployment rate fell last month to 6.5 percent as the county added 40,000 jobs to reach record payroll employment, state figures released Friday show.

L.A.’s September unemployment rate was down from 6.9 percent in August, posting its lowest level since May 2008, according to figures from the state Employment Development Department.

But the rate fell for a worrisome reason: A net 27,000 people left the labor force, either giving up on job hunting or returning to school. The number of county residents who reported they were working actually dropped by 4,000 to just about 4.7 million.

Nonetheless, the September rate was well below the 8.1 percent unemployment rate recorded a year ago. And the unemployment rate for the county’s two largest cities, Los Angeles and Long Beach, dipped below 7 percent, to 6.5 percent and 6.8 percent respectively.

Statewide unemployment dipped to 5.9 percent in September from 6.1 percent in August. The national unemployment rate was unchanged at 5.1 percent.

Meanwhile, the county gained 40,000 payroll jobs in September to reach a record 4,324,100 jobs, about 3,000 jobs above the previous high set in December. It’s the first time in nearly three decades that the county posted record payroll jobs in something approaching real time; previous records have only been noted as revisions to the data were made months or even years after the fact.

The robust job gain was chiefly due to the seasonal increase in public and private education payrolls as all schools were back in session. Adjusting for this seasonal factor, the county added 22,000 jobs.

Other sectors posting job gains in September were professional/business services (up 4,000 jobs), healthcare/social assistance (3,400) and retail trade and manufacturing (2,500 each). The financial services sector posted the largest drop of 3,200 jobs.

The picture was just as robust for the payroll jobs market over the last 12 months as the county gained 85,000 jobs for a growth rate of 2 percent. The largest gains were in health care/social assistance (up 24,000 jobs), leisure/hospitality (19,400) and food services (18,400).

The entertainment sector posted the largest decline of 2,500 jobs over the past year, despite the expansion of film tax credits designed to keep jobs in the region.