Same as why the four men attacking Hogan "ran" from Brooke. Most likely because they shouldn't risk getting unmasked. And since Snow and Kenney arrived, security may follow them shortly after. That's a minor detail that didn't even make it to TV, there's absolutely no need for nit-picking here.
As for the guy with the partially uncovered face, my first thought was Tim Donst, though upon rewatching the attack, he appears to be bigger than Donst. I'm partially basing that on comparison with the guy who's supposed to be Joey Ryan since I'm convinced it's him. His arms especially look identical to Ryan's, if you'd watched Ryan frequently, you'd have an idea of his build, that's why I'm so sure.