I think she planned extensive suicide (suicide by cop) well in advance. Every student I've interviewed who brought a gun on campus had suicidal ideation, usually documenting and usually telling other people they wanted to die, just as in this case.
Extensive suicide is not as well-studied as it could be. But one of my mentors said, "If a person is willing to kill themselves, which is a human tabu, they are willing to kill anyone and should be considered at risk of homicide as well." I agree.
I think this shooter was in that group. Hearing anyone say, "And I wanted to take these people with me" or "I want to take a lot of people with me" are two of the most chilling things I've ever heard someone say or write. Serial killers sometimes use similar language. Of course, inside jails and prisons, people say a lot of things and not everyone who says this is going to act on it. But within the workplace, I believe such statements should be taken very seriously and not laughed off (although, truthfully, most people are very afraid of upsetting such people further - the guy who shot the welfare office up near where I live - and killed a policeman in the chase following - was one such person; lots of people had heard him make threats, everyone knew he had guns, police said they could do nothing about wild talk, it's not like he walked around with his guns - this is California, he couldn't do that). He was likely on his way to shoot more people when he was himself brought down.
We know from 19th century studies by Durkheim that the rate of stranger murder (by whatever means) goes up, in urban settings and the rates soared when the car was invented. Anonymity, rapid get-away, etc. There's a lot to unpack.
IMO.