Members of the public contacted police after travellers moved on to a site in Warwickshire.
A police spokeswoman said they were contacted on Friday evening after the group moved in to a field at Kites Nest Lane, Beausale, near Kenilworth.
Residents also reported that heavy machinery, including diggers and road rollers, were on the site.
Police said they were patrolling close to the site and were trying to establish who owned the land.
There have not been any reported incidents, the spokeswoman said.