Filling in some details from my past reading ...
Apparently the final decision to use the deteriorated older bombs was made in DC.
At the time it started, F-4s and A-4s were readying to be launched for a strike. IIRC, the F-4s were along the edge of the starboard quarter and stern, and the A-4s were along the edge of the stern and port quarter, noses in and tails overhanging the sea. The zuni that launched cross starboard to port. It hit an A-4, loosing a bomb and rupturing a fuel tank, and then the section with the engine flew off the carrier, with its exhaust igniting the fuel.
The fire control people had been trained to expect an 8-10 minute delay before a bomb would bake off, but the older, deteriorated, bombs baked off in under 2 minutes and the deterioration caused the explosion to be greater than what it should have been.