Black Friday, the biggest U.S. shopping day, has taken unfortunate turns in some communities as harried shoppers seek out bargains — with at least two shootings and a pepper-spray incident that injured 20 shoppers.

Two men were shot and injured in armed robberies outside separate Wal-Mart stores, one in northern California and the other in South Carolina.

The pepper-spray incident happened at a Los Angeles-area Wal-Mart shortly after the store opened Thursday evening as shoppers prowled the aisles for discounts. Children were among those hurt by the woman's pepper spray, the Los Angeles Times reported.

"This was customer-versus-customer shopping rage," Los Angeles police Lt. Abel Parga said, according to the newspaper.

"She was competitive shopping."

Police were looking for the woman believed to be behind the pepper-spraying, but haven't been able to get a reliable description of her, the Times said.

Police in Fayetteville, N.C., were also searching for two suspects after gunshots rang out at a local mall early Friday. And a man was facing charges in upstate New York after two women were injured in a fight at a Wal-Mart.

But most of the crowds that gathered to hunt for Black Friday bargains were peaceful, with hundreds of people lining up at stores such as Best Buy and Target, which opened at midnight ET following the U.S. Thanksgiving.

In New York and St. Petersburg, Fla., reports said shopping areas were busy, with lineups as long as 2,000 people waiting for stores to open. The attraction, of course, was cut-rate prices, some as much as 70 per cent off, often the lowest of the year.

"It's hard times, so, any discount helps," one man told The Associated Press in Seminole, Fla.

He was hoping to land a cheap TV and laptop.

After showing up at Best Buy in New York on Wednesday at 3 p.m., Emmanuel Merced, 27, and his brother were the first in line when it opened. On their list was a Sharp 42-inch TV for $199 US, a PlayStation 3 console with games for $199.99 and wireless headphones for $30. Merced says he likes camping out for Black Friday and he figures he saved 50 per cent.

Shoppers check out a Black Friday deal on an iPad 2 at a Best Buy outlet in Framingham, Mass. Adam Hunger/Reuters

"I like the experience of it," says Merced, who plans to spend $3,000 to $4,000 on gifts this season.

Later Friday morning, Phoenix television station KSAZ reported that witnesses said police slammed a grandfather in a Wal-Mart in Buckeye, Ariz., to the ground after he allegedly put a game in his waistband so that he could lift his grandson out of the crowd.

The man's wife and other witnesses said that he was just trying to help his young grandson after the boy was trampled by shoppers, and only put a video game in his waistband to free his hands to help the boy.

Larry Hall, assistant chief of Buckeye police, said the man was resisting arrest and that it appears the officer acted within reason. He said an administrative review will be conducted to assess the officer's use of force, but that at first blush, it appears to be justified.

Big boost for retailers

Merchants bank on Black Friday to start the holiday shopping season, when they can make 25 to 40 per cent of their annual revenue. Despite the beleaguered U.S. economy, consumer spending in the holiday season is expected to be almost $500 billion US, about three per cent more than last year.

Indeed, a record number of shoppers are expected to head out to stores across the country this weekend to take advantage of discounts of up to 70 per cent.

Many retailers have also expanded beyond in-store sales, embracing online shopping and advertising sales on cellphones, CBC's David Common said from New York.

"Several malls are also experimenting this weekend," Common said Friday. "Tracking customers inside stores using cellphone signals, pinpointing which aisle shoppers are in by where their phone is."

Common said they would also be watching how long shoppers linger in one place and where they head next.

Canadian retailers try to woo shoppers

Meanwhile, Canadian retailers were staging their own Black Friday specials in an effort to slow cross-border shopping.

At the West Edmonton Mall, nearly every store was plastered with sale signs, CBC's Briar Stewart said Friday.

"Some advertise discounts, others are also selling an idea – Black Friday," Stewart said.

Ola McIntosh, a manager at the Sears in the sprawling Edmonton shopping centre, said the Black Friday events seemed to generate a solid response.

"The whole idea was to keep our customers – our Canadian shopping – in Canada, and it really worked. Our customers responded very well," McIntosh said.

Tony Perhar was at the Edmonton mall looking at a new plasma TV.

"My wife just phoned from work and she said there was a Black Friday sale going on. She wanted me to come and look at it," he said. "And I come and see and I'd like to buy one."

Tegin Popowich, who manages a dress shop in Thunder Bay, Ont., said she tries to entice shoppers with her own version of Black Friday bargains.

"You have so many local girls going out of town and spending all their money in the States, it's really nice to give a little extra boost to convince people to shop local, especially this holiday season," she said.

Canadian retailers can expect to lose one of every five shoppers to U.S. Black Friday-Cyber Monday discounts, with 30 per cent shopping for the holidays, the Globe and Mail reported Friday, citing an Angus Reid poll for UPS Canada.

Since the Canadian dollar rose close to parity, adding to the lure of shopping in the U.S., retailers in Canada began touting their own Black Friday deals.

But that hasn't kept many budget-conscious Canadians from making the trek south.

Bargain hunting in Michigan

Melissa Morang, the marketing and sponsorship director at Great Lakes Crossing Outlets in Auburn Hills, Mich., estimated Canadians occupied 85 per cent of the hotel rooms on the property.

'It’s been a complete zoo since 12:30 a.m. when we got here.'—Vim Mistry, a Canadian shopping in the U.S.

"A significant amount of our business [Friday] has been from our Canadian friends," Morang told CBC News early Friday.

Vim Mistry drove from Burlington, Ont., and stayed with a Michigan family as part of her cross-border shopping trip.

"The deals, they're actually pretty good," she said. "It's been a complete zoo since 12:30 a.m. when we got here."

Ottawa resident Sally Hunter was among a number of seniors boarding a bus Friday morning bound for Middleton, N.Y., and the Galleria shopping mall.

"I've got seven grandchildren, four birthdays in December, plus Christmas all over again — I need a deal," she said. "We have empty suitcases, a change of clothes and we're ready to rock and roll."

With files from The Canadian Press and The Associated Press