What fallacy is this?

P1: Many indicated that they never know what to expect from their students and thought that metal detectors would be a safe solution to unexpected circumstances.

P2: 57 percent of teachers agreed that metal detectors would help the school become a safer environment.

C: Therefore, public schools should install metal detectors for safety.

Ultimately, I would say that this is an opinion—one that has not been well-justified. This is more of a decision-making process than an argument. Pros and cons must be weighed to come to a reasonable conclusion. Does 57% agreement justify action? Is a safer environment the only goal or does that conflict with other goals (like a pleasant environment?) My house would be safer if I padded all the walls and floors, but clearly that has drawbacks. I can see an argument be made for jumping to conclusions as well.

Dr Bo's answer is a good one.

I would add that the implicit premise is that if most teachers agree with X, then X should be done. This is a questionable premise because we do not ask whether those teachers have sound grounds for accepting or supporting X, we simply see them as some kind of unquestioned 'authority' on the issue. This makes the argument far less persuasive. 

So because we are not taking our time to reason through the argument, jumping to conclusions seems like a good answer.