Hunt saboteurs trying to gather evidence of illegal fox hunting were attacked by masked quad bike riders.
Members of North East Hunt Saboteurs were at the Middleton Hunt, east of York, when their vehicle was surrounded by the masked attackers.
They used spades to smash a rear window, and the windscreen, as the female driver and her passenger tried to get away.
North Yorkshire Police confirmed they are investigating an incident of criminal damage to a vehicle on Sunday March 20.
Lee Moon, spokesman for the national Hunt Saboteurs Association, called the attack "cowardly" and said:
No-one from the Middleton Hunt could be contacted for comment.