As a fire fighter I can tell you that they did not over react at all. The signs at the bottom had a circuit board that had wires running over to a long battery pack that was wrapped up with what looks like black tape. That could have contained some form of explosive.
I live with in 10 mins from the Y-12 nuclear complex, X-10 research complex, and the K-25 enrichment plant. I work with the local fire department and have trained with home land security, and the local bomb squad on when and what to look for in any suspect package. I can tell the actions they took in Boston followed all guide lines.
What if they had not detonated the first devices? What if it was a terrorist plot? They would have very well killed several hundred people if the devices had exploded. We all need to face it the UNITED STATES will always be under attack from terrorism like it or not. So it is better to be safe and not sorry.
The time of asking questions first and acting on the answers is over. We must act first then ask questions.