FALMOUTH, Maine (AP) — Talk of fraud, vigilante observers and angry voters is prompting communities around the U.S. to move polling places out of schools or cancel classes on Election Day.

Parents and officials fear there could be confrontations or even violence that could endanger students.

Some of those anxieties are being stoked by Donald Trump’s appeal to supporters to stand guard against fraud at the polls. Authorities fear there could be clashes between self-appointed observers and voters.

Falmouth, Maine, is one of the towns to call off classes during voting. Officials say voting has also been removed or classes canceled on Election Day in such places as Illinois, Nebraska, New Hampshire, Ohio, Pennsylvania and Wisconsin.