You are called to the scene of an explosion on the 4th of July. You observe the following characteristics:

-The area where the explosion occurred is extensively damaged.
-Windows shattered in nearby homes by flying debris.
-A debris pile that appears to contain multiple nails and screws.
-Shrapnel and screws lodged in the wood siding of a nearby home.
-Witnesses reported hearing a very loud explosive sound at the time of the explosion. It was reportedly much louder than anything they had heard before.
-The remains of what appears to be a mangled and badly damaged metal briefcase are found near the explosion site.
-A second similar, undamaged briefcase is found a short distance from the location of the original explosion.

Do you feel that this explosion was due to fireworks, a drug lab explosion, gas main leak, or a bomb?