The postal service delivers ... ammonium nitrate

Authorities in South Carolina this weekend busted an 18-year-old they said was intent on attacking his high school in a Columbine-style attack.

The young man was caught when his parents opened a box he had shipped to their home. Curious about its weight, they opened it -- and were stunned to find ammonium nitrate. Their further investigation revealed papers in his room that detailed his plans

Ammonium nitrate, as you probably know, was the operative explosive that Timothy McVeigh used in his 1995 attack on the Murrah Federal Building in Oklahoma City.

Google ammonium nitrate for sale, and the search engine will return "about 95,400 results." Consider that we're talking about a product that accounts for 98 percent of U.S. industrial explosives sales, is readily available and has been used in highly destructive attacks. Now ask yourself this: How was the young man in South Carolina caught?

His parents called the cops.

How's that for homeland security?

One final note: The young man was arrested Saturday, as survivors marked the 13th anniversary of the Oklahoma City bombing and a day before the ninth anniversary of the Columbine massacre.