The school shooting in Florida has renewed the question: What should you do if you're caught in an attack?
Experts suggest making a barricade between yourself and the shooter so Inside Edition wanted to find out the safest object to hide behind.
Jimmy Grammenos of Gun for Hire Academy in New Jersey used a .22-caliber pistol and a 9 mm handgun to fire at different barricades.
After firing the .22 at a car door, all five of the bullets went through the outer layer and just three were stopped by the inner frame.
As for the 9 mm, all five bullets traveled through both layers.
“If there's an active shooter outside, you want to hide behind the engine block because that right there will actually stop a round,” Grammenos said.
He fired both guns at a wooden door and a sheet rock wall, but all the bullets went through both objects.
He also fired at a wooden table. Again, both caliber bullets penetrated the table.
A dummy was placed behind a sofa and rounds from both guns were fired into the couch. The dummy was left with bullet holes.
Grammenos fired both guns into a cinder block wall which stopped all of the bullets.
There are also bulletproof backpacks for students to wear at school.
In the wake of the massacre, some parents are buying them for their kids. Yasir Sheikh of Guard Dog Security said there has been a spike in sales.
"There is definitely a spike in sales after a mass shooting but more so after a school shooting," he told Inside Edition.
The backpacks have not been certified to protect against an AR-15, the gun used in the recent Florida school shooting.