A support truss failure is behind the closure Monday of the Baxter Bridge on Trinity Valley Road, east of Enderby.
The Ministry of Transportation said in an email that the failure has compromised the load-bearing capability of the bridge.
The ministry has called the failure a "serious structural issue."
It remains closed to all but ambulance and police vehicles, as well as pedestrians and cyclists.
"Safety of the public is our top priority," the ministry said.
"Baxter Bridge is a Howe truss wooden structure, and one of its support trusses failed through normal use, compromising the load-bearing capability of the bridge. The failure was identified Nov. 9 during a ministry inspection and confirmed by a ministry structural engineer the same day."
The closure is anticipated to last three to six weeks, the ministry says.
However, "ministry staff are exploring options to reduce the repair time and have the bridge open to traffic sooner."
Concrete barriers were to be placed at each end of the bridge, along with signs at the ends of Trinity Valley Road and start of Enderby Mabel Lake Road.
Drivers must detour via Highway 6 and Highway 97/97A.
Locals can park at the Riverside Community Hall or along Miska Road if they wish to walk across.