To force one's way into a place; to break in or intrude (used intransitively for entering by force).
昨夜、泥棒が窓から家に押し入った。
Last night, a thief broke into the house through the window.
記者たちが会見場に押し入って質問を浴びせた。
Reporters pushed into the press conference and bombarded him with questions.
彼らは居室に押し入って家具を荒らした。
They forced their way into the room and ransacked the furniture.