IDAHO FALLS, Idaho — A fast-moving wildfire burning on the Idaho National Laboratory site near Idaho Falls exploded in size Tuesday, growing to more than 90,000 acres.

The blaze, dubbed the Sheep Fire, started Monday evening with a lightning strike, according to the Bureau of Land Management. The area where it is burning is south of Highway 33 and north of Highway 20.

By Tuesday morning, the fire was an estimated 6,500 acres. But by Tuesday afternoon, it had expanded to more than 13 times that size.

The BLM and INL firefighters are responding to the fire. Idaho State Police advise anyone planning to travel on Highway 20 west of Idaho Falls to find a different route, as smoke blowing over the highway creates visibility issues. 

INL announced Tuesday that "all non-essential employees" are being evacuated from multiple facilities including the Central Facilities Area, Advanced Test Reactor Complex, EBR-1, Integrated Waste Treatment Unit and Idaho Nuclear Technology and Engineering Center. 

INL fire
INL

The evacuations came as a precaution after changes in wind and fire behavior, officials said. 

Officials expect that multiple facilities will lose power as the fire continues to burn, and are switching over to backup power. Radiation monitoring is ongoing, and based on the information obtained so far, there is no risk to the public.

Operations at the laboratory's Materials and Fuels Complex, Naval Reactors and Transient Reactor Test facilities are being curtailed Tuesday as crews fight the fire. The main site entrance is shut down to all traffic except emergency traffic.

An INL spokeswoman told KTVB that no structures are currently threatened and that the fire seems to be pushing in towards the center of the site, where there are no buildings.

The BLM called in multiple engines, water tenders and a helicopter to help fight the fire Monday. Fire officials have not released a date of containment. 

Check back for updates.