Crews have been battling wildfire "in the proximity of properties" in Truro.
Cornwall Fire and Rescue Service received reports at about 11:15 BST of a grass fire in the area of Boscawen Park, Malpas.
It said crews were working "under extreme heat and uneven surfaces" to contain the blaze.
"This is a wildfire involving pine trees, grass fire and mixed high and low vegetation," it added.
Lead Instant Commander Mark Sherris said no surrounding properties were at risk.
"The fire is in the proximity of properties, but we are constantly assessing the situation.
"We've got good working practices and firebreaks currently in process and currently there is no risk to any property."
Seven appliances have been sent, with firefighters remaining on site.
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Cornwall Fire and Rescue Service
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