NEW YORK (AP) — Kroger and L.L. Bean said Thursday they will no longer sell guns to anyone under 21, becoming the third and fourth major retailers this week to put restrictions in place that are stronger than federal laws. The announcements follow those by Dick's Sporting Goods and Walmart, emphasizing the pressure companies are facing to take a stand.

Kroger, the nation's largest grocery chain, said that since a mass shooting last month at a Florida high school that killed 17 people, it's become clear that gun retail outlets must go beyond what current U.S. laws requires.

The 19-year-old accused in the school slaying bought the AR-15 used in the attack legally. Federal law allows people 18 and older to purchase long guns such as rifles.

"In response to the tragic events in Parkland and elsewhere, we've taken a hard look at our policies and procedures for firearm sales," Kroger Co. said in a release. Kroger has sold guns from 44 of its Fred Meyer stores in the West and will raise the age to 21 for purchasing.

L.L. Bean, which says it only sells firearms at its flagship store in Maine and only guns specific to hunting and target shooting, released a statement late Thursday saying the company will no longer sell firearms or ammunition to anyone under 21.

The change comes one day after Walmart and Dick's Sporting Goods, both prominent gun sellers, tightened their company policies, and also a day after students returned to Marjory Stoneman Douglas High School in Parkland, Florida, for the first time since the shooting there.

And late Thursday outdoor retailer REI says it's halting future orders of some popular brands — including CamelBak water carriers, Giro helmets and Camp Chef stoves — whose parent company also makes ammunition and assault-style rifles. Seattle-based REI has been facing mounting pressure from some customers.

Companies like Dick's had already changed gun-sale policies in the wake of the 2012 Sandy Hook Elementary School shooting in Connecticut, but the Parkland shooting has opened a fissure between a portion of corporate America and organizations like the National Rifle Association.

MetLife, Hertz and Delta Air Lines and other major U.S. corporations have already cut ties with the National Rifle Association, and at some political risk.

Georgia lawmakers passed a bill Thursday that effectively punishes Delta for cutting ties with the NRA, following through on Republican vows to deny a tax break worth an estimated $38 million to airlines after Delta ended discounts for NRA members in the wake of the most recent school massacre. The Atlanta-based airline would have been the chief beneficiary of the tax break.

One industry analyst said after the announcement from Dick's, and strong words from its CEO about the need for change, that other retailers that devote a small percentage of their business to hunting will probably follow suit.

"It is a risky game but you can't please everyone," said Joseph Feldman, a senior managing director at Telsey Advisory Group.

The announcements from Walmart and Dick's so far have drawn hundreds of thousands of responses on social media for and against the moves, from those who pledged to buy more from one company to campaigns urging people to thank the companies for their decisions to those who vowed never to buy from them again.

Penny Stalder, a Walmart customer Thursday in Atlanta, supports the company's decision and says people mature a lot between 18 and 21.

"I am a member of the NRA, and I have a concealed carry license, I just don't see the need for young people. They can wait," she said. "There are other kinds of weapons that they can use to hunt or do whatever they want to do but they don't need military-style weapons certainly."

But Ryan Terlecki, outside a Walmart in Milwaukee, said he didn't think the three years from 18 to 21 would make that much difference. "I guess they have their reasons, you know, but as far as I'm concerned the law is that we can carry guns and that's our right and I believe we should have that right."

Other companies have tried to stay out of the debate. Some gun sellers haven't responded to requests for comment, including Bass Pro Shops, which owns Cabela's, or Camping World Holdings, which owns Gander Outdoors. The Outdoor Industry Association hasn't responded to requests for comment.

Besides major chains, guns are also bought from gun shows, local stores and from online stores.

"If large retailers, like Dick's, reduce their exposure to guns, it could impact gun manufacturers," says Maksim Soshkin, a senior analyst at IBISWorld. "Manufacturers could see a decrease in sales or have to find new avenues to sell their product."

American Outdoor Brands, which owns Smith & Wesson, said Thursday it expects gun sales to be more or less flat for the next year to 18 months. The company's third-quarter results and fourth-quarter forecasts were much weaker than Wall Street expected, and its stock fell 11 percent in aftermarket trading, while Sturm, Ruger fell 6 percent.

"We believe the firearms market will eventually return to long term growth," American Outdoor Brands Corp. CEO James Debney said on a conference call. He said the impact of the move by Dick's would very small, and it would be "pure speculation" to say what the effect might be of other companies following suit.

Kroger, based in Cincinnati, said it has been tweaking some of its gun departments as it renovates stores due to softer demand from customers.  The company ended sales of assault-style rifles at Fred Meyer several years ago in Oregon, Washington and Idaho. It will extend that ban to Alaska, where customers could get such guns via special order.

The NRA, which also didn't respond to request for comment Thursday, has pushed back on calls for raising age limits for guns or restricting the sale of assault-style weapons.

Could a person between the ages of 18 and 21 challenge the companies over the new policies and argue that they are discrimination based on age? Some experts say retailers can set age restrictions without violating the Second Amendment.

Los Angeles-based attorney Angela Reddock-Wright, who focuses on workplace discrimination disputes, said anti-discrimination laws mostly protect people 40 and older from being fired based on their age. Mike Glassman, who chairs the employment law group at the Cincinnati-based firm Dinsmore & Shohl, said the Second Amendment "only limits the government and not private entities."

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AP Business Writers Marley Jay and Anne D'Innocenzio in New York, Patrick Whittle in Portland, Maine, and video journalists Carrie Antlfinger in Milwaukee and Marina Hutchinson in Atlanta contributed to this report.

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This story has been corrected to show that Delta would have been the chief beneficiary of the $38 million Georgia tax break, not the sole beneficiary.