我昨天去了公安局报案。
wǒ zuótiān qùle gōngānjú bàoàn 。
I went to the Public Security Bureau to file a report yesterday.
公安局负责维护社会治安。
gōngānjú fùzé wéihù shèhuì zhìān 。
The Public Security Bureau is responsible for maintaining social order.
如果你遇到问题，可以联系公安局。
rúguǒ nǐ yùdào wèntí ， kěyǐ liánxì gōngānjú 。
If you encounter any problems, you can contact the Public Security Bureau.