The response to the slayings at Marjory Stoneman Douglas High School in Parkland, Fla., signaled a major shift for a state known as a legal laboratory for gun rights activists. It could become a blueprint for other states looking at new measures to address mass shootings.

A bipartisan vote of 67 to 50 in the state House ended an emotional three-week process, during which the state’s legislative leadership toured the bloodstained hallways at the high school and thousands of students marched on the state capitol in Tallahassee to demand change.

After weeks of debate, lawmakers approved a bill that would impose a three-day waiting period for most purchases of long guns and raise the minimum age for purchasing those weapons to 21. The legislation also includes millions of dollars to improve school security and train and arm school employees.