A relatively minor train derailment became a major hassle for other trains moving through Mankato on Monday.

Only three empty cars left the tracks while a private contractor moved several cars from the CHS soybean-processing plant to the Union Pacific yard along Poplar Street at about 8:45 a.m. A preliminary investigation showed human error led to a switching malfunction, Mankato police said. No one was injured.

Dan Sodeman, Union Pacific yard master, said the derailment blocked the railroad’s main line. So trains moving through the area had to be rerouted or delayed.

“Apparently one of the cars split the switch and sent the cars here and there,” he said. “We’ve been awful lucky. This is the first major incident we’ve had.”

A Dakota, Minnesota & Eastern train had to be stopped near Land of Memories Park Monday morning because it couldn’t get through, Sodeman said. The train’s crew had to leave and be replaced by a new crew once the line was cleared.

Hulcher Services, a company hired to put the cars back on the rail or remove them for repair, couldn’t get to Mankato until 3 p.m. Monday. Sodeman said he expected the problem to be solved quickly after the cars were moved.

“It shouldn’t take too long once Hulcher gets here,” he said.

Mark Davis, a UP spokesman in Omaha, Neb., said an average of three trains move through Mankato daily. The trains scheduled to move through would likely stop and wait for the rail to be cleared.

Sodeman said the rail was seeing extra traffic, however, because a “spine line” between St. Paul and Mason City, Iowa, has extra travel restrictions. There are also more grain cars moving through the area, he said.