I remember this all very well, especially when my dad stopped and got his 98K Mauser and two boxes of cartridges out of the gun cabinet before leaving for the office. Essex was already up in the Howard Johnsons building by then, so Dad thought the cops might like to borrow the rifle. Turns out, quite a few locals had already made the same offer.
Several of the officers who were shot were right across the street from the hotel, in what is now a public park area that sits in front of the state building and the Louisiana Supreme Court (since relocated). The park's landscaping now includes several tall earthen berms up near the street. I've often thought those were added out of fear of some sort of copycat.
***Yep, the NOPD officers were badly outgunned during much of this incident;***
Many of those officers storming the shaft were armed with m-1 carbines with extended magazines.