Travellers are understood to have set up camp on council-owned land in Galley Hill, Hemel Hempstead.
Police received reports this afternoon at 2.42pm, while Dacorum Borough Council is also understood to have been informed.
One woman, who asked not to be named, said: “They shouldn’t be on that land. It’s council land.
“I think it’s appalling.”
A police spokesman said: “The landowners – the local authority – are aware and all necessary actions are being taken in compliance with the law.
“Police will continue to monitor the situation and will work closely with the local authority.”