Reply #2: It doesn't sound good, but it's hard to say.

[Gormy Cuss]

I don't know your workplace but you do. What possible good reasons could have prompted this meeting? Does your department ever do confidential work for clients? That would be a reason that is harmless to you.
Is there anything about the subset of employees who were called into the meeting that makes you think it's a benign event? For example, is it possible that the company is exploring opening a new office and this group of employees have been targeted because they live in the same area? That happened in my sister's company a few years back.

Can you ask your supervisor/manager for an explanation without looking bad? The managers must know that hush-hush meetings cause concern among the excluded employees and they should be prepared to field questions.