diff --git a/src/twomartens/masterthesis/ssd.py b/src/twomartens/masterthesis/ssd.py
index 3303b85..566ec3e 100644
--- a/src/twomartens/masterthesis/ssd.py
+++ b/src/twomartens/masterthesis/ssd.py
@@ -270,6 +270,9 @@ def _get_observations(detections: Sequence[Sequence[np.ndarray]]) -> List[List[n
     for i in range(batch_size):
         print(f"{i}th batch element")
         detections_image = np.asarray(detections[i])
+        class_ids = np.argmax(detections_image[:, :-12],
+                              axis=-1)
+        detections_image = detections_image[class_ids != 0]
         print(detections_image.shape)
         overlaps = bounding_box_utils.iou(detections_image[:, -12:-8],
                                           detections_image[:, -12:-8],