An alarm is something that warns people about something that could harm them. To "be alarmed" is to be very worried and frightened about something dangerous or threatening.
* To "alarm someone" means to "cause someone to worry" or "to worry someone."
* To "be alarmed" could be translated as "be worried" or "be frightened" or "be very concerned."
* The expression "sound an alarm" could be translated by, "publicly warn" or "announce that danger is coming" or "blow a trumpet to warn about danger."