Been there, done that.
As film passes the gate, it is rolled up inside the camera. In most modern 35mm cameras, this roll of exposed film is contained only within the camera. As a result, when you open the back, you will fog the film in the gate as well as the outer layers of the roll of exposed film. But it is possible, depending on how long the back was open, how bright the light was, and the phase of the moon, that some of the frames at the center of the roll of exposed film were not fogged.
You have two choices. One is to write off that roll of film, and perhaps use it to practice loading processing spirals with the light on. The other is to continue to use the rest of the roll, process it, and see what you get.
Sometimes serendipity produces interesting results.