I don’t claim to be an expert on Columbine, but my understanding is that the bombs going off was not the problem, it was the tactical doctrine of the time that “ordinary cops” charging into a “hostage situation” would just make things worse and get more people killed.
AFAIK, this was the first major situation of its type in America. Prior to this they really were hostage situations where the appropriate response was to establish a perimeter and try to talk them out. Problem, of course, was that wasn’t what these kids had in mind.
IOW, it was the doctrine that was at fault, not the cops who followed it.
This is similar to what happened on 9/11. Doctrine, entirely reasonably to that point, was to follow the hijacker’s instructions, fly around for a few hours or days and then be released. Nobody knew they were scheduled to be part of a missile.
Once those on flight 93 found this out, it took them less than half an hour to toss the old doctrine, develop a new one appropriate to the changed situation, and implement it.
But let’s not take those on the earlier flights, or the cops at Columbine, to task for not being prescient enough to know a surprise attack wasn’t following the well-known script.
Charles Whitman?
The decision was made to go in there. When they opened the front door a pipe bomb went off, without any damage to any person. At that point the decision to go in was halted and they called the bomb squad. Meanwhile gunshots were still going off inside, and people coming out were still saying they were murdering people inside.
My point was that the Police can either move forward into the situation, or allow small incidentals to nearly indefinitely delay them - while they wait for the bomb squad or animal control.
Or just be worthless campus cops and cower behind a tree because guns are going off (OMG! Who would have imagined?) - while students stand around you with cell phones filming the action that is causing the campus cops to cower.