Under pressure to respond to a catastrophic gun tragedy, the Florida House on Tuesday debated changes to gun laws and school safety as a result of the mass shooting at Marjory Stoneman Douglas High School.

The historic House action follows Monday's narrow Senate approval of a bill that requires a three-day waiting period to buy a firearm, raises the age to buy a gun from 18 to 21 and creates a voluntary program to train school personnel to carry concealed weapons.

The bill (SB 7026) allocates $400 million for mental health and added school security measures, including police officers in all schools, and replaces Building 12 at the Parkland school where 14 students and three teachers were murdered on Valentine's Day.

The bill creates a 16-member commission with subpoena power to investigate the shooting and the response and will make annual recommendations to the Legislature for the next five years.

The 41-member House Democratic caucus voted to unanimously oppose a provision that would allow school personnel to be trained as certified law enforcement officers and carry guns on campus to neutralize threats by active shooters.

Some Republicans also will vote against the bill, a rarity in a House under the firm control of Speaker Richard Corcoran, R-Land O'Lakes.

Democrats filed amendments to eliminate the so-called guardian program, to ban the sale of all assault weapons in Florida and to require universal background checks on gun buyers. The same proposals failed in the Republican-led Senate on Saturday.

As the House debate began, Democrats quickly focused on what they say are persistent loopholes in Florida's gun laws. For example, the three-day wait applies to sales by licensed dealers but not to private gun sales.

National Rifle Association lobbyist Marion Hammer emailed Florida members Tuesday morning, blasting the Senate's action and accusing House leaders of "trying to bully Second Amendment supporters to get them to vote for the gun control package."

By inference, Hammer's criticism was aimed at Corcoran, a long-time NRA ally who backs the legislation and is considering running for governor.