NEW YORK (CNN/Money) - A group of leading U.S. economic indicators was lower in September, a research group said Monday, as the economy appeared to slow down from a late-summer surge.

The Conference Board, a private research group, said its index of leading economic indicators (LEI) fell 0.2 percent to 113 after rising 0.4 percent in August. Economists, on average, expected the index to be unchanged, according to Briefing.com.

It was the first decline in the index since March, when the economy slowed down due to fears about the impending U.S. war with Iraq.

"One of the things this points out is that we're on the road to recovery, but the road is going to be bumpy -- it always is," Conference Board economist Ken Goldstein said, adding the decline would be more worrisome if it were matched by a similar fall in October.

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U.S. stock prices were slightly lower after the report, while Treasury bond prices turned mixed, minimizing some earlier losses.

Among the 10 leading indicators that make up the index, average weekly manufacturing hours, stock prices, manufacturers' new orders for consumer goods, and materials and manufacturers' new orders for nondefense capital goods all rose in September.

The other indicators in the index -- real money supply, the gap between the yield of 10-year Treasury bonds and the Federal Reserve's key short-term interest rate, the speed at which manufacturers get supplies, consumer expectations, building permits, and average weekly initial claims for unemployment insurance -- helped drag the overall index down.

After a sluggish recovery from the 2001 recession, the economy likely grew at its fastest pace in four years in the third quarter, many economists believe.

But that growth was likely driven by one-time stimuli, such as child tax-credit checks and the proceeds from cash-out mortgage refinancing, and many economists think the economy's growth rate will slow in the fourth quarter.

Still, Goldstein said he doubted the economy would slow down to the anemic growth rates seen in the first and second quarters.