The sentence in question: 早速園内をのぞいてみました。
My attempt at translation: "At once they cleared inside the garden."
I dont really know how else to translate this sentence, however, I also have difficulties connecting with the context from before. I could see the aforementioned nursery school having "cleared" their garden of children. Basically calling them in after letting them play for some time in the garden. However, this comes pretty much out of the blue and therefore I find it rather improbable.
So maybe I just misunderstood the whole thing and someone can tell me what they actually tell us there ^^