Few is a quantifier used with plural countable nouns.
Without the article “a,”
few emphasizes a small number of something.
Adding the article removes the emphasis—
a few means
some.
The same rule applies to
little, which is used with singular uncountable nouns.
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Quoted from
Few, a Few—What’s the Difference?
Personally
I wouldn't use a few
but would say.
there were few of us.
The problem is that using the a makes the mind drift to singular that isn't quite there.
Though it could be 1 or even none it reads best as:
There were a few of us.
Mostly because us seems to exclude none or one(Unless you are a god and then you can be three but only one).
Also let's say if you were being exclusive as in...
There can be only one.
not
There can be only few.
There was one makes more sense then there was few; which would really be there were few, although there was few might bend the mind into realizing there was one(so why didn't you just say there was one).
Also
You could say this statement.
There were two of us but there was only one of us could do this.
not so much
There were two of us but there was few of us that could do this(because there is no smaller amount with a one to one comparison unless none of us could).
You might get away with
There were two of us but there was only a few of us that could do this.
since it would be similar to
There were two of us but there was only some of us that could do this.
Which is a sort of sly way of saying(only I could) or maybe one of us can't and pointing the finger at the other person.
Still, none of these choices would be for clarity as much as for some obtuse reference.