The MARC Brunswick Line saw significant delays Tuesday morning after a suspected loading mishap led to a fire on a freight train carrying cocoa powder. Montgomery County fire officials responding to reports of a train fire near Rockville Station around 7 a.m. Tuesday found smoke emanating from a container on a CSX cargo train. All rail traffic was stopped while the Montgomery County Fire and Rescue Service worked to identify the source of the fire and put it out. About an hour later, trains were allowed to get by on an adjacent track at reduced speed. Some trains were delayed up to 80 minutes during Tuesday morning commute. Delays persisted for hours as fire crews waited for CSX technicians to separate the affected segment of the cargo train for transport and offloading elsewhere. Friction with a train wheel sparked a fire in an improperly loaded container, Montgomery County Fire and Rescue spokesman Pete Piringer said in a Periscope livestream.