can a school search my son (locker, backpack, and pockets) without telling me?

[Julian]

Here is the whole whole story. It was lunch time and my son was with his friends. They were walking outside (they can be outside) and they were walking towards the back of a portable and a teacher told them to come back because they cant see them and they ran, they just ran but didn't leave campus, they went inside they building but they entered through a different entrance and after lunch was over he went to his next class and in the middle of it they pulled him out and involuntarily searched him and his friends. The talcked to each one of them individually. The principle told my son that she was searching him for something illegal because she was suspicious. They didn't find anything on any one of them so they went back to class. They each had lunch detention though for not listening. I was never notified about any of this. And also i live in Oregon