A historic, one of a kind bridge in Montana has been closed indefinitely after a tractor trailer that was more than five times the posted weight limit traveled across the bridge, damaging the structure.

The incident happened on Thursday, December 14th in at the Dearborn River High Bridge in Augusta, Montana.

According to the Great Falls Tribune, the unidentified truck driver was hauling 35 tons of rocks along Bean Lake Road for a Great Falls trucking company when he attempted to cross the 120-year-old Dearborn River High Bridge, apparently unable to see the posted signs warning of the bridge’s seven ton weight limit. The semi truck made it across the bridge, but both the decking and railing of the bridge have sustained damage.

“Whoever was driving wasn’t paying attention to the sign,” Lewis and Clark County Public Works Director Eric Griffin said.

The extent of the damage done to the bridge is not yet known, as officials are still assessing the structure, a task that is proving difficult due to the bridge’s height and its proximity to the water in the narrow Dearborn Canyon.

The bridge was originally built in 1897 as a way to connect homesteaders to the railroad. It’s made of stone, steel, and concrete and is 251-feet long.

The bridge was restored in 2003 for $1 million and is the last surviving example of a pin-connected Pratt half-deck truss bridge in the United States.

Lewis and Clark County is “still exploring the extent of what needs to happen,” and is working with the trucking company’s insurance before deciding whether or not to press charges.