Walmart said Wednesday it will no longer sell firearms and ammunition to people younger than 21, following a similar announcement by Dick's Sporting Goods that it will immediately stop selling assault-style rifles and ban the sale of all guns to anyone under 21.

Dick's CEO took on the National Rifle Association by demanding tougher gun laws after the massacre in Florida. The strongly worded announcement came as students at Marjory Stoneman Douglas High School in Parkland, Florida, returned to class for the first time since a teenager killed 17 students and educators with an AR-15 rifle two weeks ago.

"When we saw what the kids were going through and the grief of the parents and the kids who were killed in Parkland, we felt we needed to do something," Chairman and CEO Ed Stack said on ABC's "Good Morning America."

Meanwhile, putting fellow Republicans in the hot seat, President Donald Trump called for speedy and substantial changes to the nation's gun laws on Wednesday, criticizing lawmakers in a White House meeting for being too fearful of the National Rifle Association to take action.

The emphatic words from Stack put Dick's out front in the falling-out between corporate America and the gun lobby. Several major corporations, including MetLife, Hertz and Delta Air Lines, have cut ties with the NRA since the Florida tragedy, but until now, none were retailers that sold guns.

"This is the moment when business leaders across the country get to decide if they want to stand on the right side of history," said Shannon Watts, founder of Moms Demand Acton for Gun Sense in America. "Mothers make the majority of spending decisions for their families, and we want to shop with businesses that care about the safety of our families — making this a smart business move, too."

The announcement drew hundreds of thousands of responses for and against on the company's Facebook page.

Dick Sporting Goods had cut off sales of assault-style weapons after the 2012 Sandy Hook Elementary School shooting. But sales had resumed at its smaller chain of Field & Stream stores, which consisted of 35 outlets in 16 states as of October.

On Wednesday, Stack said that would end, and he called on lawmakers to act now.

He urged them to ban assault-style firearms, bump stocks and high-capacity magazines and raise the minimum age to buy firearms to 21. He said universal background checks should be required, and there should be a complete database of those banned from buying firearms. He also called for the closing of the private sale and gun show loophole that enables purchasers to escape background checks.

"We support and respect the Second Amendment, and we recognize and appreciate that the vast majority of gun owners in this country are responsible, law-abiding citizens," Stack said in a letter. "But we have to help solve the problem that's in front of us. Gun violence is an epidemic that's taking the lives of too many people, including the brightest hope for the future of America — our kids."

The NRA has pushed back aggressively against calls for raising age limits for guns or restricting the sale of assault-style weapons. Calls to the NRA were not immediately returned.

Walmart, also a big gun seller, had stopped selling AR-15s and other semi-automatic weapons in 2015, citing weak sales. Sporting goods chain Bass Pro Shops, which owns Cabela's, didn't respond to requests for comment. Nor did the Outdoor Retail Association or Gander Outdoors.

While guns can be bought from sporting goods stores or department stores, they can also be purchased online, at gun shows and from small local gun stores.

But many others were unhappy with the company's move, some posting on the Dick's page that they would stop shopping at its stores.

"I was sad to hear they would pull them off and bow to these people that have no understanding of what a gun is," said Gerald Jaeger, outside a Dick's in Brookfield, Wisconsin.

Dick's stock price was little changed as of midafternoon Wednesday afternoon, up 1.7 percent.

Meanwhile, in a freewheeling, televised session that stretched for an hour, Trump rejected both his party's incremental approach and its legislative strategy that has stalled action in Congress. Giving hope to Democrats, he said he favored a "comprehensive" approach to addressing violence like the shooting at Florida school earlier this month, although he offer no specific details.

Instead, Trump appeared to support expanded background checks. He endorsed increased school security and mental health resources, and he reaffirmed his support for raising the age to 21 for purchasing some firearms. Trump also mentioned arming teachers, and said his administration, not Congress, would ban bump-stock devices that enable guns to fire like automatic weapons.

"We can't wait and play games and nothing gets done," Trump said as he opened the session with 17 House and Senate lawmakers. "We want to stop the problems."

The president has previously backed ideas popular with Democrats, only to back away when faced with opposition from his conservative base and his GOP allies in Congress. It was not clear whether he would continue to push for swift and significant changes to gun laws, when confronted with the inevitable resistance from his party.

Still, the televised discussion allowed Trump to play the role of potential dealmaker, a favorite for the president. Democratic lawmakers made a point of appealing to the president to use his political power to persuade his party to take action.

"It is going to have to be you," Sen. Chris Murphy told Trump.

Trump's call for stronger background checks, which are popular among Americans, has been resisted by Republicans in Congress and the NRA. Republicans have instead been leaning toward modest legislation designed to improve the background system already in place. Trump made clear he was looking for more and accused lawmakers of being "petrified" of the gun lobby.

"Hey, I'm the biggest fan of the Second Amendment," Trump said, adding that he told NRA officials it's time to act. "We have to stop this nonsense."

The White House meeting came amid fresh public debate over gun laws, fueled by student survivors of the massacre at Florida's Marjory Stoneman Douglas High School, who have been meeting with lawmakers on Capitol Hill. The school reopened Wednesday for the first time since a Valentine's Day assault killed 17.

Gun legislation has lost momentum in Congress as Republican leaders showed little interest in pursuing stricter gun control laws.

Democrats said they were concerned Trump's interest may fade quickly. After the meeting, Murphy, D-Conn., told reporters: "I'm worried that this was the beginning and the end of the president's advocacy on this issue. The White House has to put some meat on the bones. The White House has to send a proposal to Congress."

The White House is expected to reveal more on the president's plans for school safety this week, though it has not announced any plans. That announcement will likely include goals for background checks and bump stocks, though whether age restrictions will be specifically addressed remains unclear, according to an administration official who sought anonymity to discuss private conversations.

Trump rejected the way Republican leaders in Congress have framed the debate, saying the House-backed bill linking a background check measure with a bill to expand gun rights by allowing gun owners to carry concealed weapons across state lines was not the right approach. The concealed carry measure is the gun lobby's top legislative priority. But "you'll never get it passed," Trump told lawmakers, reminding them that Democratic senators, including some in the room, strongly oppose it.

Instead, he suggested Republicans should focus on the background check bill, then load it up with other gun control and safety measures.

Ever the marketer, Trump suggested that the leading bill adjusting the National Instant Criminal Background Check System — now known as "Fix NICS" — could use a new name. "Maybe you change the title, all right? The U.S. Background Check Bill, or whatever," Trump said.

The hour-long meeting with lawmakers was reminiscent of one in January on immigration, when he told lawmakers to come up with a good bill and he would take the "heat" from critics.

That effort, however, ended in failure in Congress amid Trump's shifting views and priorities in the debate.

Among those at the White House Wednesday were Sens. Pat Toomey, R-Pa., and Joe Manchin, D-W.Va., who are pushing their bill — which failed twice in the Senate after the 2012 Sandy Hook Elementary School shooting — to broaden background checks to include pre-purchase reviews at online and gun show sales.

Trump asked Toomey if his plan to expand background checks included raising the minimum age for young people to buy an assault weapon. Toomey told the president it did not.

"You know why," Trump scoffed. "Because you're afraid of the NRA."

The meeting came after one major retailer, Dick's Sporting Goods, announced it was halting sales of assault-style rifles and high-capacity magazines at all of its stores and banning the sale of all guns to anyone under 21.

The discussion was billed as a session focused on "school and community safety," and two of those attending, Sen. Orrin Hatch, R-Utah, and Rep. John Rutherford, R-Fla., have proposed new federal grant funding to stem school violence. The bill would offer money for law enforcement and school staff training, campus infrastructure upgrades and mental health resources.

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Associated Press writers Ken Thomas, Alan Fram, Andrew Taylor and Zeke Miller contributed to this story. AP Retail Writers Anne D'Innocenzio and Joseph Pisani contributed to this report. Associated Press reporter Carrie Antlfinger contributed from Brookfield, Wisconsin.

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Follow Mascaro on Twitter at https://twitter.com/LisaMascaro and Daly https://twitter.com/MatthewDalyWDC

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