NEW YORK -- In a first look at the back-to-school sales season, three major retailers on Wednesday reported modest sales gains for August.

"My sense is that the back-to-school season is still adversely affected by the onslaught of layoffs," said Jeff Feiner, managing director at Lehman Brothers.

Kohl's Corp. and Costco Wholesale Corp. reported gains that fell short of analysts' expectations, while Sears, Roebuck and Co. reported a slight rise in sales at stores open at least a year, known as same-store sales.

Same-store sales are considered the best indicator of a retailer's health.

Most of the nation's largest retailers are expected to report their August sales figures today.