WINDSOR (CBS4) - A train went off the rails in Windsor Sunday night, landing within inches of the backyard fences of homes near Windsor Middle School.

The derailment also shut down 7th Avenue, a main artery in and out of the town.

It happened just after 7 p.m. as the train cut through Windsor on its way northwest towards Timnath and Fort Collins.

Investigators were on scene at 10 p.m., trying to determine what caused the train to derail -- as others worked to move the train cars and clean up the mess. The train was loaded with tons of fracking sand.

Luckily, only a handful of cars derailed and no one was injured.

The roads reopened Monday morning but crews were still working to upright the toppled train cars after daybreak.