An investigation is under way after more than 100 panes of glass were broken at a church in Co Offaly.
The incident occurred at St Catherine's church in Tullamore.
It is believed the windows were smashed some time between Monday and yesterday morning.
It has been estimated that repairing the windows and installing security measures could cost up to €70,000.
Reverend Isaac Delamere from St Catherine's Church says he felt "incredibly sad and numb" after the discovery of the broken windows.
Speaking on RTÉ's News at One, he said that every window that was not covered by wire mesh is damaged.
Rev Delamere said he believes it was probably young people "messing or having a laugh", but the scale of the damage and the number of stones that were flung into the church show that it took a long time to do the damage.
He said that there was no question that it was a sectarian attack and the entire community was shocked and saddened by it.
