Streets of Rage 3

So I was facing the Level 6 boss on hard mode, jump kicking like crazy with Blaze. I was mainly targeting Jet but killed a lot of Rockets in the process. After I KO’d the last Rocket I noticed they weren't coming back. Everyone told me they were infinite but it seems they're not. Has anyone else tried this? Seriously though once all the Rockets are gone you'll find Jet is a really easy Boss to beat.