Three tour guides have been ticketed in the last week for helping visitors get into Acadia National Park, which is closed because of the government shutdown.
Chief Park Ranger Stuart West says the operators of two tour buses, one from Florida, the other from Maine, were stopped.
So was a local taxi driver.
West says the shutdown brought an automatic suspension of commercial operator permits.
That means those who bring people into the park in exchange for money are at risk of a $125 fine.
Visitors who enter the park on foot or bicycle are not being cited.