Because of the recent Hurricane, our building was officially closed for a day. We do engineering and so are all considered exempt employees, frequently working 45-50 hours per week when it's busy, and only being paid for 40.
Our HR department sent out an e-mail today, stating that exempt employees will have to use either vacation time or unpaid time for the day the building was closed. We have some new people who simply don't have the time accrued to use.
Can they really have it both ways? My understanding was that exempt employees might not get paid if they work overtime, but at least if something like this happened, they would continue to get paid 40 hours regardless.

What I was able to find elsewhere:
The Fair Labor Standards Act or FLSA sets the standards for salaried workers who are exempt from overtime. The FLSA does not require employers to pay workers for any time that the employee is not actually working. This includes holidays, or days that the business is shut down for any reason. If the business closed for 3 days due to a power outage or flooding, for example, the employer would not be required to pay workers for that time, even if they were salaried.
The FLSA does not permit employers to dock salaried workers for hours or partial days missed. However, it does allow employers to dock a salaried workers pay when the worker misses an entire day of work
If you do dock an exempt employee for any reason, other than for a major safety violation, that employee loses their exempt status for that pay period, not just that week. If that occurs, then you will have to pay any overtime to that employee that may be due for that pay period. If you make a habit of "docking" exempt employees for absences of less than one day, you risk losing the exemption completely, which could make you liable for back overtime pay over a longer period of time