The story...

There are many, many first-hand accounts of explosions at the WTC, perhaps indicating the existence of pre-positioned bombs.

Our take...

There are certainly lots of these accounts, but what they prove is another matter. Here are some of our concerns.

#1, it's true that lots of people used words like "explosion" and "bomb" to describe what they saw and heard at the WTC, but none of that proves actual explosives were used. You can hear an "explosion" without a bomb being required, and saying something was "like a bomb" doesn't mean you think it was one.

Don't believe it? Here’s some examples of how “bombs” and “explosion” reports aren’t necessarily to be taken literally.

#2, of course many quotes display no such doubts, and seem very certain about what they’ve heard. However, not every account you read is accurate. And others are selectively edited, perhaps leaving you with a misleading impression of what the witness truly thinks. Here are a few examples.

#3, you don't think that can explain everything. And you're quite right. But be careful when you read these quotes, because one-liners like "I heard another explosion" or "we thought there was a secondary explosion" aren't necessarily meaningful. In fact, at least one account commonly quoted as proof of "bombs in the building" could have a much simpler truth behind it, and explain other stories. Here's why.

#4, be similarly cautious about video footage. There is one clip of a firefighter saying “bomb in the building, start clearing out”, for instance, which supposedly adds weight to the controlled demolition case. But the truth is a little different.

#5, even if someone is definitively referring to the moment of collapse, and talking about seeing something like a secondary explosion run around the building, that doesn't necessarily mean bombs. This is one alternative explanation.

#6, William Rodriguez tells a more famous story of hearing an explosion before the plane hit. Does it entirely make sense, though? And could there be another way of looking at this?

#7, Mike Pecoraro also talks of an “explosion” in the basement levels. Could this have been caused by jet fuel? NIST suggested that possibility:

Like the Concourse Level, elevator lobbies throughout the building were particularly affected,38 likely by excess jet fuel ignited by the crash pouring down the elevator shafts.39 While only 3 percent (n=11) of the survivors reported seeing fireballs in their immediate area at the time of the airplane impact, the observations from the face-to-face interviews show the extreme nature of these events:

A survivor from a floor in the 80s: “The entire corridor became an inferno outside our front door. Smoke began to enter our office. There was also debris falling. ... The fire on the corridor was at least 10 ft high, and it ran the … good length of the corridor. Then I saw a fireball come down the elevator shaft and blew the elevator doors. The fireball came right at me; it was a really bright color.”
Interview 1000055 (NIST 2004)

A survivor from a floor in the 40s: “I saw the elevator in front me had flames coming out from it. The elevator was closed but the flames came from the front where the doors meet and on the sides. They reached about a foot and a half, with the flames standing from the floor to the ceiling. I saw a chandelier shaking; it was really moving. The corridor was dim. I also heard people screaming from the [nearby] floor. I felt the
heat on my face and I thought that my eyebrows were going to get burned. Black smoke starting filling the corridor, it got really dense really fast.”

Interview 1000109 (NIST 2004)
A survivor in the basement: “I saw a big bright orange color coming through the basement with the smoke ... A fire ball came shooting out of the basement door.”
Interview 100760 (NIST 2004)
http://wtc.nist.gov/NISTNCSTAR1-7.pdf

Mark Roberts compiled this collection of accounts as further evidence.

One argument against the jet fuel theory is based around this NIST quote:

There were seven freight elevators, only one of which served all floors.
wtc.nist.gov/NISTNCSTAR1-1.pdf

It’s then suggested that the account of the operator of Car 50 (Arturo Griffiths), which ran the full length of the building, proves there was no explosion in this lift shaft. And therefore, as no other lifts “served all floors”, jet fuel could not have reached the basement via elevator shafts.

The obvious weakness with this argument is its attempt to say that, if an elevator doesn’t “serve all floors”, then the shaft could not provide a path for jet fuel to reach the basement. NIST tell us that Car #49, for instance, served basement floors 1-5, and floors 41-74. But then what? Is it safe to assume that a lift servicing no floors higher than 74 is effectively hermetically sealed at that point? Or could there still be a path the fuel might have taken? We’d suggest you’d need a close look at the building blueprints (and perhaps talk to engineers familiar with the WTC) to tell that for sure.

What’s more, the Car 50 referred to here is not the only elevator that travelled from the basement to the impact area:

In addition to the passenger elevators, there were seven freight elevators in each tower; most served a particular zone, while Car 50 served every floor.

• Car #5: B1-5, 7, 9-40, 44
• Car #6: B1-5, 44, 75, 77-107
• Car #17: B1-1, 41, 43-78
• Car #48: B1-7, 9-40
• Car #49: B1-5, 41-74
• Car #50: B6-108
• Car #99: 107-11016
http://wtc.nist.gov/pubs/NISTNCSTAR1-7.pdf

As you can see, Car 6 may have left out many floors, but it still travelled almost the full length of the building. And keep in mind that was the case for most of the elevator shafts. The WTC used a “stacked” system where, while most elevators may only have visited a portion of the floors, the shaft itself extended the full length of the building. So there would be one elevator dealing with the bottom third, another the middle third, another the top, all within the same shaft. 

And there may be another conduit available in the utility shafts. NIST wrote that “fuel flowed across the floors and down elevator and utility shafts” in connection with fires on the upper floors, but how far down did they go? You’d imagine right to the bottom if they’re containing things like telephone or electrical cables, pipes and so on, but we can’t say for sure whether they offered an unrestricted route, or not. It remains another possibility to consider, though.

#8, some people talk about "bombs in the basement", or at least on the lower levels, during the WTC collapse. It’s been suggested that smoke visible outside the towers may have been the result of thermite, for instance. But where are the matching reports from inside the towers? There were people who survived in the stairwells and lower levels, and we’ve yet to see any of them talk about explosions or smoke from below as the buildings collapsed. And if the buildings were weakened at the basement levels, why did the very lower stories remain standing?

Let's also not forget #9, the explosion reports are spread from (just before) impact right up to the collapse itself. Is it characteristic of controlled demolition to set of bombs apparently randomly over about an hour? Or does it make more sense to believe that accounts of explosions some time before collapse were related to impact damage, the fire, fractured gas mains or whatever? 

And then there's #10. How many witnesses who talk of bombs, detonators and so on, had experience they could use as a comparison? How many would know what a bomb might sound like in that environment, and how it would different from the sound of a collapse?

That seems particularly relevant to us. If thousands of tons of a burning building were to collapse onto the floor below, then steel columns will fail, there will be a loud boom (or perhaps several), debris will fly out, flames will be pushed into the air. How are witnesses going to describe this, without using words like "explosion", or "bomb"? Given that by this time most people realised it was a terrorist attack, is it at all surprising that some may even have believed (at the time) that bombs were involved?

There’s no need to take our word for it, either. 911Myths.com visitor Brandon Wright discovered a video of another collapse preceded by what sounds like enormous explosions (and were described by at least one witness as “like bombs”), yet actually came from metal failing under extreme stress. Read more, and listen to the audio evidence yourself here.

On balance, then, the witness reports don't surprise us at all, and there's no doubt the collapse (and some events prior to it) involved what looked, and felt like explosions. That doesn't begin to prove that bombs were the cause, though -- it'll take considerably more evidence to do that.