The biggest shopping day of the year has begun, as stores began to open their doors as early as 8 p.m. on the evening of Thanksgiving in an effort give customers as much time as possible to get their hands on Black Friday deals.

And shoppers wasted no time tearing themselves away from their families to take advantage of the sales, with stores such as Walmart, Target and Sears packed with desperate bargain-hunters.

While initial accounts indicated that the crowds were largely peaceful, avoiding the riots seen in previous years, many stores had an unusually heavy police presence, and there were some reports of scuffles between customers in packed-out shopping aisles.

And amid the shopping frenzy, two customers – a husband and a wife – were hit by a car in the parking lot of a Walmart on the edge of Seattle on Thursday evening, with the wife being airlifted to hospital after the accident which saw her pinned under the vehicle.

Stores from Target to Toys R Us opened their doors on Thanksgiving evening, hoping Americans will be willing to shop soon after they finish their pumpkin pie.

Target opened its doors at 9 p.m. on the holiday, three hours earlier than last year. Sears, which didn’t open on Thanksgiving last year, opened at 8 p.m. on Thursday through 10 p.m. on Black Friday.

Toys R Us opened at 8 p.m., an hour earlier than last year. And others such as Macy’s are opening at midnight on Black Friday.

When Macy’s flagship Herald Square store in New York opened its doors at midnight, about 11,000 shoppers showed up.

Overall, about 17% of shoppers plan to take advantage of Thanksgiving hours, according to a International Council of Shopping Centers-Goldman Sachs survey of 1,000 consumers.

Shoppers queued up at Toys R Us in New York’s Times Square on Thursday evening

Retailers are trying everything they can to lure consumers into stores by making shopping as easy as possible.

In addition to expanding their hours into Thanksgiving, many are offering free layaways and shipping, matching the cheaper prices of online rivals and updating their mobile shopping apps with more information.

“Every retailer wants to beat everyone else,” said C. Britt Beemer, chairman of America’s Research Group, a research firm based in Charleston, S.C. “Shoppers love it”.

Indeed, there were 11 shoppers in a four-tent encampment outside a Best Buy store near Ann Arbor, Michigan. The purpose of their wait? A $179 40-inch Toshiba LCD television is worth missing Thanksgiving dinner at home.

With 41million people expected to shop on what has been dubbed “Gray Thursday”, police have responded to fights and threats between bargain-hungry customers, some of whom have camped outside stores for days.

The spats add to the discontent surrounding the stores, with employees frustrated about working on Thanksgiving, and Walmart workers threatening to protest over their pay, schedules and benefits.

Outside a Kmart in Indianapolis, which opened at 6 a.m. on Thursday, officers responded to a brawl between shoppers as some attempted to sell vouchers the store had handed out for limited items.

“Everybody started going crazy about it, and then the cops got called in and it just became a madhouse,” one shopper told News 8.

And at a Kmart on Stockton Boulevard in South Sacremento, one shopper threatened to stab people while waiting in line for K-Mart’s doors to open and told people he “wasn’t joking”.

Police arrived at the scene shortly after the threat – made after shop staff came outside to hand out “doorbuster deal” vouchers to the first in the line – to help control the crowds.

In a bid to minimize trouble, the Los Angeles Police Department deployed helicopters over some malls, while a cavalry of police officers on bikes and horses monitored from streets below.

According to the L.A. Times, others scoured crowds from rooftops and signs warned shoppers against becoming victims of theft.

It comes after a series of previous Black Friday incidents; at a Wal-Mart in the city last year, scores of people were injured when a woman pepper sprayed her competition in a bid for discounted video games. Two years ago, gunfire broke out at a Toys R Us, killing two people.

“For some people, shopping is a competitive sport,” LAPD Cmdr. Andy Smith told the paper.

“But it should not be a contact sport.”

Officers are also working with stores to keep violent outbursts under control, and Best Buy even participated in training drills to handle the large crowds.

The Walmart where the pepper spray incident occurred will hand out vouchers for some items to avoid a scramble. If customers do not get a voucher for the item, they should expect there will be none left, management told the Times.