Throughout the day, the Stoneman Douglas students moved through the labyrinthine building, and met for 20 or 30 minutes at a time with lawmakers in their offices. They crowded around small conference tables and packed onto leather couches or sat cross-legged on nubby carpets.

Some lawmakers asked for photographs they could use for promotional materials. At least one, a Democrat, pulled students into a picture before even introducing himself.

Group No. 6 crammed into the elevator with two parent chaperones. They met with Representative Patricia H. Williams, a Democrat, and Senator Debbie Mayfield, a Republican. Ms. Mayfield said that changes were needed, perhaps including raising the minimum age to buy powerful weapons, but she rebuffed criticism from a student, Daniel Bishop, 16, that such a change would not actually prevent deaths.

“We can’t stop crazies,” she told the group.

Afterward, Amanda De La Cruz, 16, looked distraught. “I want the ban on semiautomatic weapons,” she said. “I don’t care about the crazies.”

Will Weatherford, a former speaker of the Florida House, said on Tuesday that the ferocious public response to the Parkland shooting exposed pent-up feelings of horror and fear that have mounted over time. Mr. Weatherford, a conservative Republican, said legislators might be able to move quickly on a few tailored proposals, such as raising the legal age for possessing assault rifles.

“With Pulse, with what took place in Las Vegas, there’s been an aggregate effect,” Mr. Weatherford said, referring to the mass killings in 2016 and 2017 at an Orlando nightclub and an outdoor concert in Las Vegas. “All of it is adding up and there’s a lot of frustration that’s boiling over.”

Mr. Weatherford said he expected the Legislature to take action of some kind, but cautioned: “It’s hard to write a thoughtful policy in three weeks.”