Students at Holmfirth High School have been told to avoid crossing a neighbouring recreation ground after travellers moved onto the site.
Staff at the school are supervising students arriving and leaving the school and have also alerted parents to the situation.
Kirklees Council has begun legal proceeding to evict the travellers, who moved their caravans and trucks onto the council-owned site off Springwood Road on Wednesday afternoon.
A number of travellers’ vehicles are also occupying part of the car park at the Leeds Road Retail Park in Huddersfield.
A Holmfirth resident claimed the travellers on the recreation ground had driven through a barrier that had been left open, damaging the barrier in the process.
He said he had asked Kirklees if they could lock the barrier to prevent more vehicles arriving, but was told that could not be done.
The resident, who asked not to be named, said: “There is extreme anger from all the people around here.”
A spokesperson for Kirklees Council said: “The council is aware of an encampment at Sycamore Recreation Ground, Wooldale, Holmfirth. We have begun the legal process to remove the travellers from this site.”
The owner of Leeds Road Retail Park is also understood to have begun action to move the travellers from that site.