The demand for protective gear

Joe Curran is the president of Bullet Blocker. He started his business by making two bulletproof backpacks for his own children. It was a few years after Columbine, and he was nervous about their safety. Then, other parents started to get in touch with Curran.

"Friends and family all asked me for some for their kids," Curran said. "And they said, 'You should start a company.'"

On Bullet Blocker's website, the backpacks sell for around $180 and up. The company also sells vests, helmets, and lab coats. Curran says sales rise after a shooting. Before the Sandy Hook shootings, Curran says he sold around 20 backpacks a week, but in the three weeks after, he says he sold closer to 10,000.

Other sellers of body armor have seen similar sales trends.

Shalini Solomon is eCommerce manager at Security Pro USA, a body armor company.

"I see more growth in your average consumer that probably would never even think that I have any relation to someone who might own a gun or come shooting up my place," Solomon said. "Those are now the people that are thinking: 'Am I safe at work?' Or, 'Am I safe in my own church?'"

A day after San Bernardino, Solomon says sales rose 600 percent.