Why are there armed police sentries on Wuhan Yangtze River Bridge?

You can check several bridges on the Yangtze River. Each bridge is an artery running through the north and south of the Yangtze River, and its position is very important. For such an important place, if something happens, such as terrorists blowing you up, it will be fatal, so for such an important local government, its security work will be strengthened, so there will be armed police standing guard.