A little more info, not much.
http://www.roaringcamp.com/application/files/2214/5135/6067/RCR-12_28_15-Press-Release.pdf

Monday, December 28
For Immediate Release
FELTON, CA – Six passengers who were standing in a train car sustained minor injuries when the train came to an abrupt stop half way along the route. Emergency responders were requested to the site by Roaring Camp staff to ensure guests were evaluated and treated for any injuries. Three guests were taken to the hospital for further observation as a precautionary measure. Cause of the abrupt stop appears to be due to a mechanical malfunction at this time, but further investigation of equipment is under way. Roaring Camp would like to thank Felton Fire Department for their swift response.
Immediately following the incident the Railroad was inspected and cleared to operate, and the 2 p.m. ran without incident. Roaring Camp Railroads remains open and is continuing normal operations.
According to Roaring Camp CEO, Melani Clark, “Passenger safety is our top priority and despite an exemplary safety and maintenance record, we regret today’s incident occurred. Our sincerest apologies to all of our passengers, and especially those who were affected. In the meantime, all of us at the Railroad are grateful for the outpouring of concern we have received from the public.”