None of the structures at the Fort Osage National Historic Landmark will have to be demolished after being damaged in a fire Sunday afternoon that closed the site indefinitely.

Jackson County spokesperson Marshanna Hester said county parks staff found the buildings at the reconstructed 1812 fort in Sibley to be structurally sound, though the officers' quarters suffered significant interior damage. One of the blockhouses suffered damage to the roof, which might need to be replaced.

Hester said the only permanent damage happened to some items for the historical interpreters' reproductions, such as uniforms and beds. No archives or artifacts were damaged.

The Fort Osage Education Center next door to the fort was not damaged by the grass fire, but smoke entered the building, so it also is closed indefinitely. The nearby cemetery was not affected by the fire.

Sunday's fire started as a grassfire along the Missouri River bank and moved up the bluff to the fort, fanned by windy and unseasonably dry conditions. Staff reported the fire about 5 p.m., and fire crews from multiple agencies responded. Chief John Yocum of the Fort Osage Fire Protection District said investigators have narrowed down where the grassfire possibly started but the exact cause officially is undetermined.