Google and Amazon have taken steps to censor gun-related topics on their platforms, but they still make it easy for would-be terrorists to find instructions for building pipe bombs.

Authorities arrested Florida man Cesar Sayoc Jr. on Friday for sending explosive devices to a number of high-profile Democrats, including former President Barack Obama, former Secretary of State Hillary Clinton and billionaire Democratic donor George Soros.

A packaged addressed to former CIA Director John Brennan was also sent to CNN, though Brennan is actually an MSNBC contributor. (RELATED: Chuck Todd Says Mail Bombs 'Could Be Some Sort Of Russian Operation)