Alleged Dril or non-drilll for military base UFO approach

This is not really a UFO sighting report—however, I thought I would relate the following story:  In the 1980s, my wife and I took an evening walk to a restaurant in our neighborhood for some iced tea and a piece of pie.  We ran into my aunt who lived in an apartment building just down from the restaurant—she was having light refreshment with a neighbor. We joined them.
While we were visiting, a couple of teenagers sat down in the booth behind me.  One of them told a story that I of course cannot verify or check out.  I had a little trouble keeping up with the story because I didn't want to be rude to my aunt and her friend.
But this was his story:   One weekend, he went to visit a girlfriend who lived with her family in the base-housing section at one of our air force bases. At the time, we had three air force bases in our state, plus one Marine Air facility.   Because I missed a portion of his story, I'm not entirely certain, but I believe he was talking about one of our air bases.
Anyway, he said, he and his girfriend went to the base movie theater on either a Friday or Saturday night.   When the movie let out, he and his girlfriend and virtually all of the people who attended the showing began their return to their homes in the base housing area.  As they were walking, a siren began to sound.  Immediately, all of the people headed toward various base houses.  He said that there was no hesitation.  His girlfriend chose a house and two or three other people followed them to the front door.  The girl did not knock, but simply opened the door.  The family acknowledged them and invited them to sit.  Someone in the house closed the drapes in all of the living room windows and left the room, presumably to close them in the other rooms of the house.  The teenager made the point that there were drapes and not blinds.
There were various conversations in the livingroom.  I cannot remember whether or not the family they had walked in on offered water or other refreshment.
Sometime later—it was not clear to me how much later, as he was telling the story  but it seems as if it could have been close to hour—the siren sounded again.  The visitors thanked the family and everyone left.
His girlfriend told him that what just happened may or may not have been an exercise. She said she was not really supposed to know, but she had learned that the exercise or non-execise was a procedure when a UFO approached the base. The teeanger asked, “You mean, like a landing?”  The girl did not really answer the question.
As I said, I have no way to knowing whether or not the guy was telling a true story, but perhaps others know of similar procedures at other military bases.
Witness indicates that the date is approximate.  PD