Safe WorkPlace?

I work in a Production Plant in Utah,
The other day about 2hours into the shift a bombthreat
was called in th the Security Office who then called in to
the HR department. None of the workers on the production
floor was told about it, or told to leave.
Then about 2hours latter another one came in and they
finally did have everyone leave the building and meet outside about 20 feet from a side door while the upper managers and 1 cop went through the building.This building is over 5000sq feet.1 hour latter they came back out and had everyone go back in to finnish working.
Should they have had everyone leave the first time the
threat came in?

I am a law school graduate. What I offer is mere information, not to be construed as forming an attorney client relationship.

Did you suffer any damages?

If this is merely a question to satisfy your curiosity and your future safety with the company, I think OSHA would cover this:http://www.osha.gov/

It might even be a matter of local law covering police investigations: if police substantiate as real threat, then evacaution is necessary. But before that, it is voltunary.