I'm trying to understand this sentence: 言ったのは少女のひとりだった。, which is translated as "It was one of the girls who said it.".
I've understood the first 2 parts:
- 言ったの = noun-ified (past tense of talking) = the talking that happened in the past
- 少女のひとり = a singular girl
However, I don't understand the function of the だった.
Tofugu says だった is a past tense marker, but here 言った is already past tense, so I don't see the purpose.
Tae Kim says だった means "something was something" but that interpretation doesn't make sense here.
What is the purpose of the だった here?