By a "short space of time" I meant how long such shooting sprees normally last. It took Cruz just 6 minutes to kill all those people and he was apprehended about a hour later. Those attacks in the article above took place over a few weeks so yes I would call it a "spree" but not in the same way. Serial killers (Cruz is one of course but I mean Yorkshire Ripper types) however often have long periods of inactivity between killings. Sometimes it may even be years so even if you still class it as a spree its different. BTK hadn't killed anyone for 14 years at the time he was apprehended (after the police tracked him down via a floppy disk he sent to them in the mail) though there's evidence he was planning to kill again. The floppy disk story is strange for someone who was pretty meticulous (he was a bit of a jobsworth apparently in his working life not that most are serial killers lol) but the evidence shows he didn't want to be caught at that time. Maybe later on he would have and I might have read that he intended to leave evidence of him being the killer following his own death. He was actually SURPRISED the police lied to him about the extent they can retrieve floppy disk data.
Note that in the UK cases I'm sure all those places are considered "Middle Class". Certainly they were not "sink estates" rife with crime in large cities or towns. All 3 people held grudges against their community which isn't exactly an uncommon reason for mass shootings. 2 of them killed relatives as well.
On the subject of teachers carrying guns, etc here's an article from a former Columbine High School student. Not all people caught up in such cases are anti-gun. I bet some of the people who were hiding in the closets at Parkland were pro gun and a few of them might even still be. I'm pretty sure the majority probably aren't but don't assume all of them will be protesting against the NRA, etc.
http://blogs.denverpost.com/thespot...umbine-student-wants-firearms-schools/116942/