TORONTO -- One of Canada's largest tech retailers has incurred the wrath of Black Friday shoppers who say a website malfunction that spanned several hours prevented them from taking advantage of the annual markdowns.

The online backlash against Best Buy Canada began shortly after the company tweeted Thursday night that its Black Friday sales were in effect.

By midnight, many were complaining that the site wouldn't allow them to make purchases and tweeting photos of themselves shopping on competitors' websites.

Some suggested that the retailer, which also owns the Geek Squad computer support company, should be able to avoid tech-related problems on one of the busiest shopping days of the year.

Best Buy Canada posted on its website about 15 minutes after midnight that it had encountered an "issue" but expected to be up and running soon. It asked shoppers to be patient as staff tried to fix the problem.

An update 2 1/2 hours later said "many" customers were now able to complete their purchases and that it was working to resolve any lingering technical issues.

The company said later Friday morning the site was fully functional and blamed record web traffic for the hitch.

But many online had jumped ship much long before then.

"Waiting for your site to work. Wandered over to Amazon. SAME PROMOS, and a working website! .bestbuy," one person tweeted earlier.

"I bought my stuff from Walmart. Same prices and their site works," another person said on Twitter.

"@BestBuyCanada you ARE a technology based online business right? This sale proves you're in the wrong business. #WorstBuy #YOUHADONEJOB," another shopper said.

At least one person said their credit card had been charged for several orders that failed to go through, and the company referred them to customer service.

Best Buy Canada wasn't the only site bogged down by hordes of bargain-hungry shoppers.

Many reported that Canada Computers' website was down, and the company tweeted that it was experiencing "technical difficulties."

Walmart's U.S. site also faltered, though its Canadian equivalent appeared to hold up.