(CNN) It's only the first day of school at Fond du Lac High School in Wisconsin, but already something's amiss: a snake is loose somewhere inside.

Principal Matthew Steinbarth told CNN a three-foot long ball python named Kai escaped its cage in the science lab over the weekend.

Steinbarth said class is still taking place in the lab since the snake is not a danger to the students. He said the snake is gentle, and he is not concerned with its disappearance.

The snake is the pet of a biology teacher at the school, who brings it in on occasion to show the students. Steinbarth said the snake escaped by knocking the lid off its cage.

The school called the fire department, but they were unable to locate the serpent with their heat sensors.

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