The Scottish Fire and Rescue Service was called out at 5.28pm on Tuesday near Mill Road, by Loch Direcleit, between Tarbert and Kendebig.
A spokeswoman told the Press Association the fire “spread rapid on the moor” and four pumps were in attendance along with beaters and a hose reel.
She said Police Scotland were also in attendance to help with traffic management as “smoke covered the road”.
Twitter user Katrina Craig said the blaze was “dangerously near homes”.
Speaking to the Press Association, she said: “No one was evacuated as far as we could see.
“They were beating the fire at the side of the road, it wasn’t out of control though.
“When we first drove up, the flames were blowing towards the road, you could feel the heat.
“Fire crew let oncoming traffic through, although traffic coming from Tarbet was still held up. Fire is still on-going on the hill at various points.”