Can さん mean in?

[Zoopnigh]

The entire sentence is "閉まるドア 小指はさんだ", and I know that it is saying "I shut my little finger in the door", but I'm not exactly sure what san means here. I looked up several different meanings of "san" and I couldn't find anything that worked with this sentence.

 

[Mike Cash]

Past tense of はさむ is はさんだ

 

[Zoopnigh]

Oh, that's why I hate when they use hiragana for kanji. Thank you.

 

[Mike Cash]

It also would have been more obvious had they not dropped the を