U.S. job openings surged to a record high in March, suggesting that a recent slowdown in hiring was probably the result of employers having difficulties finding qualified workers.

Job openings, a measure of labor demand, increased by 472,000 to a seasonally adjusted 6.6 million, the Labor Department said on Tuesday in its monthly Job Openings and Labor Turnover Survey, or JOLTS.

March’s job openings were the highest since the data series started in December 2000 and pushed the job openings rate up three-tenths of a percentage point to 4.2 percent. Job growth slowed in March and April after an outsized gain in February.

Reuters (Reporting By Lucia Mutikani; Editing by Andrea Ricci)