Sagging sales of autos held down overall US retail sales in August, with American consumers buying goods and services at their slowest pace in six months, government data showed Friday.

However, the Commerce Department said it was unclear to what extent Hurricane Harvey had affected the monthly numbers, with the storm both hurting and helping sales for some retailers.

Meanwhile, internet stores like Amazon saw their largest sales drop in three years.

Total US retail sales sank 0.2 percent compared to July, falling to a seasonally adjusted $474.8 billion. Analysts had expected a modest 0.1 percent increase.

The monthly result was still up 3.2 percent over July 2016.

The report also drew a more somber picture of the prior two months, with sharp downward revisions for June and July, suggesting consumption may offer less support to GDP growth in the third quarter than initially hoped.

Excluding the volatile auto sector, retail sales rose 0.2 percent, down from July's 0.4 percent.

Ian Shepherdson of Pantheon Macroeconomics said the soft numbers were "puzzling" given a reported boost in sales ahead of the storm and suggested that GDP growth in the third quarter would be closer to two percent than to three percent.

"We would not be at all surprised to see these numbers revised up in due course and over the next couple of months we'd expect decent gains, not least because sales of building materials and cars are about to rocket," he wrote in a research note.

Recovery and rebuilding efforts following hurricanes Harvey and Irma should boost such sales.

Analysts had been expecting August's poor auto sales to weigh on retail sales, with the final sales weekend of the month lost in the Gulf Coast region due to Harvey.

Auto sales fell 1.6 percent for the month, the largest decrease since January. Electronics and appliance stores, building materials and clothing were also all down.

With rising fuel prices, however, gas stations saw their biggest bump since December, up 2.5 percent for the month.

The Commerce Department reported Friday it could not isolate retail and food services activity by geographic region, meaning the storm's full impact was unclear.

"Some firms reported a drop in sales due to permanent or temporary store closures and closures due to damage, shipment delays, etc.," the department said in a statement.

Response rates to monthly surveys were consistent with prior months, it added.