1.   FBI officials have said the exploding canisters failed to explode and bounced off the bunker and into the water.

2.   Military tear gas canisters were used because the non-pyrotechnic tear gas canisters failed to penetrate the bunker, according to Justice Department officials.

3.   The canister failed to explode because of a defective detonating device wedged under the track.

4.   The canister failed to explode and the fire was quickly put out.