Three juveniles have been identified as being responsible for setting on fire and severely damaging a historic 113-year-old wooden bridge in a swampy swath of northern Minnesota.

The onetime vital rail crossing in Blackduck, a modern-day favorite among hikers and snowmobilers, caught fire April 13. By the time the blaze was extinguished, nearly 30 percent of the 700-foot-long bridge was destroyed. Investigators quickly classified the blaze as arson.

A tip from the public led to identification of the three juveniles, police said. It’s now up to the Beltrami County attorney’s office to consider charges.

The Blackduck Trestle, also known as the M & I Trestle, was built during 1901-02 for use by the Northern Pacific subsidiary M & I Railroad. In February 2014, long after the trains stopped rolling, the bridge was added to the National Register of Historic Places. Police said it was valued at $500,000.

The span, the longest on the former M & I line, traversed Coburn Creek and the surrounding marsh while providing a rail link between Bemidji and International Falls, according to the register. The crisscross style of supports was a common design in rail bridge construction.

The bridge’s description in the register also noted it was one of the longest of its kind still standing in the state.

In 1996, the Minnesota Department of Transportation assumed ownership of the bridge after the railroad ceased operations. MnDOT was in the process of turning the span over to the state Department of Natural Resources, however, that process is being delayed because of the arson.

MnDOT spokesman Reid Baumann said there are many agencies with a stake in the bridge's future and also options for what to do with the blackened span.

Among the choices, Baumann said: Close it off permamently, rebuild and modernize, or restore it to its original appearance.

"We need to have a lot of conversations first to see what direction we want to go and see the funding issues as well," Baumann said Thursday.

Paul Walsh • 612-673-4482