WASHINGTON — The number of people seeking unemployment benefits fell sharply last week, an encouraging sign that layoffs are easing.

The Labor Department says that weekly applications dropped 37,000 to a seasonally adjusted 391,000, the lowest level since April 2. It’s the first time applications have fallen below 400,000 since Aug. 6.

Applications typically need to fall below 375,000 to signal substantial job growth. They haven’t been that low since February.

A Labor Department spokesman says some of the drop was due to technical difficulties related to seasonally adjusting the figures. The spokesman says some states also reported higher applications in previous weeks due to Hurricane Irene.

The four-week average, a less volatile measure, fell to 417,000, the first drop in six weeks.