An anti-hunting group said it was the victim of an "unprovoked, premeditated attack" in Cambridgeshire.
North Cambs Hunt Sabs said its car was attacked with metal tools at the Fitzwilliam (Milton) Hunt at Lutton.
Police are investigating alleged criminal damage and assault that left a man with "minor injuries".
A hunt spokeswoman said it does not condone the type of behaviour alleged, even with "extreme provocation", and would help police with inquiries.
James Taylor, from North Cambs Hunt Sabs, said the group went to Lutton, near Huntingdon, in response to a report of a hunt on Saturday.
"Suddenly we were being followed by four four-wheel drives and then they boxed us in," said Mr Taylor.
Video footage appears to show the back window of the group's vehicle being smashed before they were pursued away from the scene by one vehicle.
The North Cambs Hunt Sabs Facebook page said the footage showed an "unprovoked, premeditated attack".
A Cambridgeshire Police spokesman said: "We have been contacted with reports of an alleged incident of criminal damage and assault that happened at about 16:15 GMT on 10 February, near Lutton.
"An altercation took place between two groups of people, which resulted in a vehicle being damaged and a man being assaulted. The victim received minor injuries as a result of what happened.
"The incident is being investigated by officers."