Please explain this phrase

[espen180]

I was watching an anime, and there was a woman holding a sign saying:

すいません でした。

Which means "I am sorry", but I am wondering about the use of the -ta base of です. Can someone explain why the use of です in this phrase?

ありがとう。


EDIT:

It means 'was', right?

[Toritoribe]

You got it. Because it's past when the accident she apologizes for was happened. Plus, すいません without です could be interpreted as "excuse me" in that case.

[espen180]

そう です。 Thanks for the answer.

ありがとう。 :-)