After hearing the heartbreaking stories of school shooting survivors and of parents who have lost children in massacres, President Donald Trump said Wednesday that the country should seriously consider arming educators and training them to use weapons to deal with mass shootings.

If Aaron Feis, the assistant football coach at Marjory Stoneman Douglas High School, had a gun, he might have been able to prevent the deaths of 17 students and educators at the Parkland, Fla., school, Trump said during a listening session at the White House with a group of parents, students, and others affected by school violence.

“If the coach had a firearm in his locker when he ran at this guy ... If he had firearm, he wouldn’t have had to run. He would have shot. That would have been the end of it,” Trump said. “It’s called concealed carry where a teacher would have a concealed gun on them. And it would no longer be a gun-free zone. A gun-free [school] zone, to a maniac, a gun-free zone, is let’s go in and attack because people aren’t coming at us.”

Trump said that most shootings last only a few minutes, but it can take longer for police and other first responders to come on the scene. “If you had one teacher who was adept at firearms, they could very well end the attack very quickly,” he said.

He suggested that teachers armed with weapons should be highly trained, possibly former Marines, or other armed forces veterans. And he added, “If these cowards knew that the school was well-guarded, they wouldn’t go into the school to start off with. It could very well solve the problem.”

Trump’s comments came as he met with a group of more than 40 that included parents, students, and teachers connected to the shootings at Stoneman Douglas High School last week, as well as the massacres at Sandy Hook Elementary School in 2012, and at Columbine High School in 1999. Vice President Mike Pence and U.S. Secretary of Education Betsy DeVos, who had lunch with some of the attendees earlier in the day, were also on hand.

On Wednesday morning, Trump sought to clarify his remarks, stressing on Twitter that he did not want to arm all teachers, just “20 percent” of highly trained educators and school staff.

I never said “give teachers guns” like was stated on Fake News @CNN & @NBC. What I said was to look at the possibility of giving “concealed guns to gun adept teachers with military or special training experience - only the best. 20% of teachers, a lot, would now be able to

— Donald J. Trump (@realDonaldTrump) February 22, 2018

....immediately fire back if a savage sicko came to a school with bad intentions. Highly trained teachers would also serve as a deterrent to the cowards that do this. Far more assets at much less cost than guards. A “gun free” school is a magnet for bad people. ATTACKS WOULD END!

— Donald J. Trump (@realDonaldTrump) February 22, 2018

Arming school staff is a solution that the National Rifle Association proposed after 20 children and six adults were killed at Sandy Hook.

But some grieving parents at the White House meeting said it is not the solution.

Nicole Hockley, whose 6-year-old son Dylan died at Sandy Hook, argued that teachers need training and resources, not weapons.

“Rather than arming [teachers] with a firearm, I would arm them with the knowledge of how to prevent these attacks in the first place” by making sure that troubled students get the mental health and counseling services they need, said Hockley, a co-founder of Sandy Hook Promise, a nonprofit that works to protect children from gun violence.

Mark Barden, whose son Daniel, 7, was also killed at Sandy Hook, said his wife, Jackie, is a teacher.

“She will tell you that schoolteachers have more than enough responsibility right now than to have the awesome responsibility of lethal force to take a life,” said Barden, another Sandy Hook Promise founder.

He noted, too, that the shooters at Sandy Hook and Columbine killed themselves after the attacks, so it’s unlikely that knowing teachers in the schools were armed would have deterred them.

And Sam Zeif, a Stoneman Douglas student, suggested that gun control has to be part of the solution. It doesn’t make sense that someone his age should be able to go into a store and buy an assault rifle, he said.

“I don’t understand why I can still go to a store and buy a weapon of war,” he said. “How is it that easy to buy this type of weapon? How did we not stop this after Columbine, after Sandy Hook?” Zeif said that he wasn’t sure if he could ever go back to Stoneman Douglas.

Other Douglas students and parents have been vocal since the shooting about the need for stricter gun laws.

But some at White House listening session, which was nationally televised, seemed to agree with Trump that arming teachers is the right move.

“One possible solution would be to have people in the school who have volunteered to have a firearm in the classroom,” said Frederick Abt, a Stoneman Douglas parent, whose son survived the shooting. That way, “when something like this starts the first responders are already on campus.”

It doesn’t have to be teachers, he said. “A custodian could be an undercover policeman. If you can’t stop it from happening and with hundreds of millions of guns out there, I don’t know if it will ever be fully stopped. ... Unfortunately, you can’t wait five or six seven minutes.”

Shortly after the listening session, advocacy groups quickly decried Trump’s pitch to arm educators.

“All students deserve to go to a school in a place without guns,” said Judith Browne Dianis, the executive director of Advancement Project’s National Office. “Communities of color know all too well that schools with armed police and metal detectors don’t make students feel safe. Making schools feel like war zones or prisons is not the solution. We need counselors and support systems for students, not more police.”

And Lily Eskelsen García, the president of the 3 million-member National Education Association said, “Bringing more guns into our schools does nothing to protect our students and educators from gun violence. ... We need solutions that will keep guns out of the hands of those who want to use them to massacre innocent children and educators. Arming teachers does nothing to prevent that.”

Broward Superintendent Robert Runcie, speaking before a CNN rally with survivors of the shooting, said Wednesday that he does not support proposals to arm teachers.

“We don’t need to put guns in the hands of teachers,” he said. “You know what we need? We need to arm our teachers with more money in their pockets.”’

But at the Conservative Political Action Conference in National Harbor, Md., Wayne LaPierre, the executive vice president of the National Rifle Association, called for educators and parents to come together to place “effective, trained armed security” in schools “that will absolutely protect every innocent child in this country.” He urged schools to ask the NRA for help in setting up those protections.

President Donald Trump speaks as he hosts a listening session about school violence with high school students, teachers and parents in the State Dining Room of the White House in Washington on Feb. 21. --Carolyn Kaster/AP