Firefighters are attempting to dampen the flames of a 'large gorse fire' on Dartmoor.
Devon and Somerset Fire and Rescue service has six fire engines, plus additional appliances at the scene of the fire at Mary Tavy.
It's affecting traffic and travel from Tavistock to Okehampton.
Traffic monitoring site Inrix is reporting that the A386 in both directions at Lydford is closed, and there is queueing traffic due to serious fire between Blackdown and Beardon (Mary Tavy).
There have been several gorse fires in Devon and Cornwall over the past few weeks. It is swaling season, where planned and controlled fires are lit to to manage vegetation on the moors.
Nationally, controlled burning takes place, though on Dartmoor a voluntary code ends burning on the 31 March to allow for the ground nesting bird season.
But some gorse fires were believed to have been caused by arson.
Last week, Cornwall Fire & Rescue Service said a gorse fire at a nature reserve near Wadebridge was thought to have been started deliberately.
Rosenannon Downs, which is owned by Cornwall Wildlife Trust, suffered the third major fire to devastate the heathland in the past three years.
Around 15 hectares of land, which is equal to the size of 37 football fields was burned, along with 250 metres of fencing used to keep the site stockproof. It also allowed local graziers to graze the site with native North Devon cattle.
There were also gorse fire incidents on the Lizard Peninsula earlier this month - at Goonhilly on Wednesday 16th March and and Ruan Minor on Tuesday 15th March.
And on Tuesday last week, a major incident was declared in Devon due to a large gorse fire next to a busy A road.
The road was closed between Roborough and Yelverton and there were 10 fire crews at the scene.