This isn't the work of terrorists using sophisticated materials. The ingredients and the know how to build extremely powerful explosives are easy to come by.
A joint investigation by CBS News and affiliate KCNC found the chemicals needed to build a bomb right out in the open at a Denver-area gun show, along with the printed instructions on how to make them explode.
"What I do is go ahead and put in plugs and all and then put the fuse in and glue it in," explains an unidentified buyer.
While it is legal to buy each of the chemicals individually, it's illegal to buy them together as components for explosives. But at this show the vendors don't ask and the customers don't tell.
An unidentified vendor says anybody buying these ingredients at a gun show would not have a legitimate reason to do so, "unless they purposely wanted to make flash powder."
Flash powder is most commonly used in fireworks, but must be mixed by a licensed explosives expert. Just how volatile is it?
At CBS' request, Sgt. Mark Singer of the Adams County, Colorado bomb squad supervised a demonstration. First, for comparison, he detonated two pounds of dynamite. Then he exploded the same amount of flash powder, which created significantly more damage.
Experts say even a small car could be packed with as much as 500 pounds of explosives.
"Obviously, we want to avoid the big brother thing, but on the other hand we can't ignore situations that could be deadly to who knows how many people," says Singer.
Colorado lawmaker Dan Grossman worries about what amounts to one-stop shopping at gun shows like this one.
"The point is do we make it convenient?" asks Grossman. "Do we create a 7-11 for terrorists?
"Do we create a super store for militia members who want to cause harm to this country and their neighbors? The answer to me is no."
Authorities say they are watching, and prosecute illegal sales when they find them. But back at the gun show, one of hundreds held around the country, that threat doesn't seem to carry much weight.