It look like similar happen in 2001
(Sunday, September 2, 2001) - At Cedar Point Park in Sandusky, Ohio, thirty park employees were left stranded on the Millennium Force roller coaster after a cable broke, stopping the train which was carrying the workers about 275 feet up the 310-foot tall lift hill. All of the passengers were evacuated from the ride in about an hour, and none of them was injured. The ride is closed, pending repairs.
http://www.rideaccidents.com/2001.html#sep2b