WASHINGTON — The fewest Americans in more than five years applied for new unemployment benefits last week, a surprising decline that may reflect seasonal quirks more than a sudden improvement in the jobs market.

Initial jobless claims — a rough gauge of layoffs — sank by 18,000 to a seasonally adjusted 324,000 in the week ended April 27, the Labor Department said Thursday. That’s the lowest level since January 2008.

Economists surveyed by MarketWatch had expected claims to rise to 345,000 from a revised 342,000 in the prior week.

Claims often gyrate sharply in the month after Easter because of the Good Friday holiday and spring break, making it harder for Labor officials to adjust claims for seasonal oddities. Yet the effects usually fade by early May.

Labor officials said there were no usual factors in the claims data. The decline in claims might suggest some improvement in the labor market, mainly fewer layoffs. The report is less reliable as an indicator of hiring, though, and other employment indicators have signaled companies are creating fewer jobs compared to just a few months ago.