What did they see at the end of the second middle school?

I think the biggest possibility is the intern teacher. After all, there are intern teachers in the title of the film. It is also possible that the third girl in the photo, Shi Run, didn't see her when she was rescued. Maybe she came out of the water to get back at Xi Shi's cowardice. The photo floating on the water is a sign. Maybe the male teacher locked the door. Remember? Like 1, security guards are responsible for sealing off the scene. At the last moment, he will come out to pick up the students who are not dead. Only the teacher who locks the door outside can stop them.

The whole film doesn't explain the relationship between the teacher who locked the door and others at all. He was there when the swimming teacher just died.

Other suspects are the same as others. Who can give this teacher a reasonable explanation? ...

But these are just my guesses. Movies want us to imagine ourselves. It wants to tell people that evil people are rewarded ~ ~