There was an incident involving two of Al Capone's men with Luca Brasi (dispatched by Vito Corleone) in the novel.

As SC put it once, the "axe" and the "towel" incidents were real incidents that did take place. I didn't have the chance to ask if they happened simultaneously (as in the novel) or if they happened to Al Capone's men.

I appologize for those who didn't read the novel for not disclosing more details but this is a great part of the novel and you don't want to miss it.