Another day of grieving outside Robb Elementary School in Uvalde brought mounting frustration from mourners, who question the police response to the school massacre. MORE: https://www.khou.com/article/news/special-reports/uvalde-school-shooting/active-shooter-instructor-uvalde-cisd-officers/285-080a542f-f2fe-462e-b733-7cf90ec1e7f6