Mangilao was rocked by a series of explosions Friday, but don't be alarmed - it was all part of an FBI training program on dealing with potential terrorist threats.

The demonstration at the Hawaiian Rock quarry culminates a four-day training course to familiarize participants with the dangers of improvised explosive devices, and included a workshop on the common chemical substances used to make them. FBI Special Agent John Kowatch said, "From hydrogen peroxide to chlorine bleach and these things have everyday uses but in the wrong hands they can do the wrong things with them and make improvised explosives. And they pose a real danger to people."

The explosions showed exactly how. TSA deputy assistant Robert Cothran attended the training and says the public can help by keeping an eye out for suspicious behavior, like people buying up unusual amounts of chemicals, for example. "It might not mean anything to you, but somebody behind the scenes might have more information that you might not know about that might put the pieces together," he detailed.

The national awareness campaign If You See Something , Say Something also urges the public not to take anything for granted.