The various Alistaires scatter, one a bit more clumsily than the rest. That one in particular makes a break for the stairs. The amount of smoke and debris at this point made any invisibility a moot point, so he charged in plain sight. A few precise shots were enough to suppress the advances of any other guards, until the more trained forces could move on them.

He makes it to Shinobi's office in time to see the door to the tunnel shut. He tries to wrench it open by hand, fails, and then tries to figure the access method.