Its night, a great time for stealth, or perhaps, something else thats optional?

You have planned a bank heist, many people are working and lots of guards are around..The building is really tall, atleast 3 stories tall..Everyone is inside working..At the front is 4 innocent workers, but 2 of them are on break..leaving two in the open..The staircase is inbetween the 4 counters.