What does the word precipitated mean in the following sentence? The incident at the school precipitated the need for more security

The word "precipitated" in this sentence means "brought about." To precipitate means to cause something, and in this case, the incident caused the school to hire greater security so as to prevent these things from happening. "Lessened" and "oppressed" are quite the opposite of what happened, whereas the incident happened before, not after more security was brought, which is why "happened after" is also incorrect.