Did Eric & Dylan have keys to the school?

I know it was mentioned in the aftermath of the shooting that the boys might have had keys to the school and essentially brought in the bombs after prom. I recently found this little tidbit on Tumblr as well:

Quote :

At the Hugh M. Woods hardware store at 4950 S. Kipling St., a customer-service worker told police he repeatedly sold propane tanks, wire, screws, nails and duct tape to two boys he identified as Harris and Klebold. Police said those types of materials were used in the 67 bombs found unexploded at the high school, in Klebold’s car and in Harris’ home.

The employee said he also copied keys - marked “Do Not Duplicate” - for the two teens. Police earlier confirmed they’ve been searching for a missing set of keys to the school, which authorities speculate may have allowed the killers to carry so many bombs into the school before the attack.

"For the last three months, I bet they came in more than a dozen times," said Gary Sowell, 50, the hardware worker. "They were buying the same things, pretty much the same things. That’s what got my attention.

"Believe it or not, they said they were for school. I didn’t pursue it any more than that.

"I duplicated some keys for them, two sets of keys. On the keys it said, "Do Not Duplicate.’ I knew they were security keys, but I didn’t question them. They brought in a set of five keys."

Interesting how it says that authorities were searching for a missing set of keys to the school. Could it be possible that E & D had keys, possibly for the video productions or whatnot? What do you guys think?

Possibly. I mean, there's so much irony and mystery in Columbine. Why was is at that moment Eric walked in to lay down the duffel bags, the security cameraman replaced the types? And also the weird fact that most people didn't see Eric placing the bags. In my humble opinion, there surely must be a possibility that the planting of the bombs was done pre-massacre.