Two loaded shotguns, ammunition and a number of knives and blades have been removed from a graveyard in Park, County Londonderry.
A crowd of more than 200 people gathered in the grounds of St Mary's church on Altinure Road on Saturday morning.
A liquid believed to be acid was also removed from the site.
The PSNI said a number of officers were deployed "to keep people safe and prevent disorder".
However, tensions between two groups escalated and officers had to intervene using their batons.
There were no reports of any injuries and no arrests were made.
PSNI Ch Insp Alan Hutton said: "We were aware of community tensions in the area ahead of a planned event.
"It was necessary for officers to intervene and use minimal force including the use of their batons, given the number of people involved.
"Police enquiries into the incident are ongoing."