It certainly wasn't a robbery, because a robbery is when you personally confront someone and take something from them.
It certainly wasn't a burglary, because that's when you break into a property with the intent of stealing things inside, and then steal them. Whoever was just randomly smashing things had no intention of actually stealing anything, and did not in fact actually steal anything.
And the general result of a burglary gone wrong is the burglar flees or attempts to flee. They don't murder the first person who just coincidentally happened to show up alone (after making a social media post basically advertising they'd be there soon) in the most brutal and vicious way imaginable.