It happened at Saint Agnes Cemetery at 1050 Pottstown Pike in West Goshen Township.
Investigators said the thefts were discovered after employees there started getting reports from family members that American flags were removed from their holders and simply stuck in the ground.
Metal thefts have been on the increase, but police say no local scrap yards have reported anyone trying to sell the flag holders.
Anyone with information is asked to call the West Goshen Township Police at 610-696-7400.
