"Cafe and fire alarm"

My husband and I visited outpatient department today when we finished we went for lunch at the cafe on the ground floor we was eating our lunch when the fire alarm went off there were quite a few people in the cafe at this time the staff never asked any one to leave but the staff left so we picked our drinks up and headed for the exit when we got there the staff had put a barrier strap across so we couldn't get out we had to ask a member of staff to let us out I think this unacceptable and should be addressed