US President Donald Trump has said arming teachers could prevent school shootings like that which left 17 people dead last week in Florida.
A staff member with a gun could end an attack "very quickly", he said.
Mr Trump floated the proposal as emotional survivors of the 14 February massacre implored him to make sure it never happens again.
The Republican president also backed calls for improved background checks on gun buyers.
The US president also endorsed a proposal long championed by the National Rifle Association (NRA), a powerful gun lobby group.
He pledged to look "very strongly" at calls for educators to be armed with guns.
"If you had a teacher who was adept at firearms," he said, "they could very well end the attack very quickly."
"Where a teacher would have a concealed gun on them," he said, while acknowledging the plan was controversial, "they would go for special training and they would be there, and you would no longer have a gun-free zone.
"A gun-free zone, to a maniac, because they are all cowards, a gun-free zone is, 'let's go in and let's attack.'"
A dozen US states already allow concealed handguns to be carried on college premises, according to the website Armed Campuses. The state of Florida does not.
The US president listened to pleas for gun reform on Wednesday from about 40 students, teachers and families in the executive mansion's state dining room.
Some of those at the hour-long event voiced support for Mr Trump's idea of arming teachers.
Hundreds of teenagers from the Washington DC suburbs rallied outside the White House before Mr Trump's meeting.
Meanwhile, survivors of the shooting poured into the Florida state capital to demand lawmakers restrict sales of assault rifles.
Some lawmakers in Florida's state legislature said they would consider raising the minimum age to buy assault rifles - like the one police say was used in last week's massacre - from 18 to 21.
However, the legislators rejected a proposal on Tuesday to even debate banning such weapons..