ブザーbuzzer, personal alarm (loud buzzer to attract attention in case of attack)

このブザーは、火災(かさい)を知(し)らせる警報(けいほう)音(おん)です。

This buzzer is an alarm sound that notifies of a fire. {buzzer, personal alarm (loud buzzer to attract attention in case of attack)}

ブザーが鳴(な)っている。建物(たてもの)に不審(ふしん)者(しゃ)が入(はい)ったのだろう。

The buzzer is ringing. There must be an intruder in the building. {buzzer, personal alarm (loud buzzer to attract attention in case of attack)}

刃物(はもの)を持(も)った人(ひと)が入(はい)ってきたので、急(いそ)いでブザーを鳴(な)らしました。

Since a person carrying a knife came in, I quickly rang the buzzer. {buzzer, personal alarm (loud buzzer to attract attention in case of attack)}

玄関(げんかん)のブザーが鳴(な)りました。それなのに、玄関(げんかん)の前(まえ)には誰(だれ)もいませんでした。

The front door buzzer rang. However, there was no one in front of the entrance. {buzzer, personal alarm (loud buzzer to attract attention in case of attack)}

ブザーが鳴(な)っているという事(こと)は、何(なに)かしらの緊急(きんきゅう)事態(じたい)が起(お)きているという事(こと)だ。

The fact that the buzzer is ringing means that some sort of emergency is happening. {buzzer, personal alarm (loud buzzer to attract attention in case of attack)}