Students had left the RancheView School about a half-hour before it was visited by a delegation of anti-vac lobbyists.
A letter has been sent to parents by school principal Sharon Cronin outlining the circumstances.
On June 10, one person entered the school's office and asked to speak to the school principal. She was asked to wait outside, but when Cronin went into the front foyer five people were waiting.
They didn't provide their names, and when one person started talking about vaccines, they were politely asked to leave.
She assured parents the only access to the school is through the front door, and anyone entering has to go through the office. She says they do have a sign posted asking people to phone the office in advance, but some people do walk through a few times a week.
"We have our protocol in place for how to handle this, and I can assure you that the safety of our students and staff is our top priority," she states in the letter.
That same day, the anti-vac delegation attempted to meet Mayor Jeff Genung, but he was tied up in meetings and wasn't aware they had dropped by until afterward.