Because of the practice, police were able to respond quickly to very specific information from the school and parents knew exactly where to pick up their children.
But regardless of the drills and the quick, organized response, the bombing has shaken an upscale community's sense of security.
In a community of million dollar homes, police, roadblocks, worry and uncertainty did not seem to fit.
Parents received an automatic telephone call from the school district, saying essentially, "no injuries, school closed, pick up your child." Soon, hundreds of the parents lined the fence outside Abbot Middle School.
"My daughter, who graduated last year, said they practiced this three or four times, so it's amazing how smooth this is actually going, I'm happy about that" parent John Stirlacci said.
It became a mass early-dismissal as 1,200 students were evacuated. Many of them did not take the event nearly as seriously as their parents.
But nobody liked the disruption in this normally quiet neighborhood, nor the sense that it does not feel quite as safe today, as yesterday.
"It's very disturbing because you just wonder if your kids get to high school, or even middle school, will they be safe," neighbor Michelle Moalem said.