I bet this inexperienced cop....pulled his gun and had his finger in the trigger-guard (contrary to training, I’ve read, to put your finger inside the guard unless you are sure you’re going to shoot...). He was nervous and jumpy, got startled, and accidentally pulled the trigger when the woman came up from the side.
Inexperience and bad-training...
I cannot believe even the worst cop—Muslim or not—would purposely with premeditation shoot an unarmed woman.