(Adds details on specific stocks, updates prices)
* TSX down 33.57 points, or 0.22 percent, to 15,178.30
* Eight of the TSX's 10 main groups move lower
TORONTO, Sept 1 (Reuters) - Canada's main stock index headed lower on Friday in a broad retreat as a string of gold miners and retailers pulled back a day after the index hit a three-week high.
At 10:18 a.m. EDT (1418 GMT), the Toronto Stock Exchange's S&P/TSX composite index was down 33.57 points, or 0.22 percent, at 15,178.30.
The index is still on track for a 0.9 percent gain on the week, buoyed by robust earnings reports from the country's biggest banks and evidence of rapid growth in the domestic economy.
Gold miners weighed even as the price of bullion held firm after U.S. job growth slowed more than expected in August.
Barrick Gold Corp fell 0.9 percent to C$22.28 and Agnico Eagle Mines Ltd lost 1.5 percent to C$63.08.
Groceries retailers, under pressure after Amazon cut prices on some items at its just-acquired Whole Foods Market chain, also lost ground. Loblaw Cos Ltd fell 2 percent to C$66.37 and Metro Inc was down 1.5 percent to C$40.62.
Eight of the index's 10 main groups were in negative territory, with two decliners for every advancer overall.
Industrials fell 0.5 percent while the materials group, which includes precious and base metals miners and fertilizer companies, lost 0.4 percent.
The most influential gainers included Toronto-Dominion Bank , which extended gains from Thursday after reporting strong quarterly results. It was up 0.5 percent to C$67.39.
BRP Inc, the maker of Ski-Doo vehicles, advanced nearly 1 percent to C$41.87 after reporting earnings and revenue that exceeded analysts' expectations.
And Alaris Royalty Corp jumped 8.7 percent to C$22.61 after the financing company said it had funded a new partner and CIBC analysts raised their price target on the stock to C$23. (Reporting by Alastair Sharp; Editing by Jeffrey Benkoe)