I don't see why they would've been evacuated from that area. The first quantum filament hit and a few seconds later the 2nd one hit that killed Lt Monroe. If anything the Engineers would've been trapped in Engineering, or on that deck, with all the emergency bulkheads going into place. Getting to Engineering would be a priority for any survivors, hence why Riker and Data went there.
FWIW the containment door wasn't lowered either.