WASHINGTON — Retail sales dropped in September by the largest amount in seven months, possibly signaling that rising trade tensions and turbulent markets are having an impact on consumer spending.

Retail sales fell 0.3% last month following a 0.6% gain in August, the Commerce Department reported Wednesday. It was the first decline since a 0.5% drop in February.

The spending decline in October, which was unexpected, was influenced by special factors including a big 0.7% decline in sales at gasoline stations, a decline that likely reflected falling gas prices during the month.