tensorflow object detection api giving false error of 99%

I trained a model to detect pistols on tensorflow object detection API using mobilenet model and after running for 20k steps I tried to test it,it is showing 99% accuracy on every image which does not contain pistols.why is this happening? Also it is predicting at the same place for every image i have added an image of detection here. also the dataset was around of 3k labeled images.

IMAGES OF DETECTION