BERRIEN COUNTY, Mich. — Part of an ancient Michigan cave where “The Great Train Robbery” was filmed has collapsed under heavy rain.

A wall of Bear Cave in Buchanan collapsed this week, Adam Morris, the property manager at a campground that operates near the cave, told MLive.com. The wall collapsed at night and was already closed to the public due to flooding, Morris said. He didn't clarify what night the collapse happened.

The cave will remain closed pending an inspection, Morris said. It was unclear how soon the inspection might take place.

Storms on July 9, 10 and 15 dumped up to 7 inches of rain across Berrien County. Michigan’s average July rainfall is between 3 inches and 4 inches, according to the National Weather Service.

The Bear Cave formed more than 25,000 years ago, according to the campground. It served as an Underground Railroad stop for escaped slaves and bandits hid there in 1895 after robbing an Ohio bank, according to the campground. That story led producers to film part of the 1903 silent film “The Great Train Robbery” in the cave.

A large population of Eastern Pipistrelle bats make their home in the cave.