WASHINGTON (AP) — Fewer Americans signed contracts to buy U.S. homes in August, the third straight decline. The drop could mean that higher mortgage rates are starting to deter buyers.

The National Association of Realtors says its seasonally adjusted index for pending home sales declined 1.6 percent to 107.7 last month. The index has fallen for three straight months after reaching a 6 ½-year high in May.

Mortgage rates have risen more than a full percentage point since May. That caused many buyers to speed up purchases this summer, pushing sales of previously owned homes to the highest level in over six years in August.