It happened on Monday on land used for military training and Dorset and Wiltshire Fire and Rescue Service says it has been told by the army that there is a fire in the impact area near Urchfont.
The Ministry of Defense confirmed it had suspended live firing until the fires were extinguished.
A Ministry of Defense spokesman said: “We are monitoring a number of fires on the Salisbury Plain training area and can confirm there is no risk to the public at this time.
“We are monitoring the fire and are in close contact with Dorset and Wiltshire Fire Brigade who are ready to assist should the fire spread beyond the impact area.”
Due to the location, the fire department is not attending. Firefighters cannot enter the affected area due to the risk of unexploded ordnance.
It comes after a safety warning was issued by the fire service amid heatwave in the area.
People are being asked to take extra care around campfires, bonfires and barbecues as a new orange fire alert has been issued.
A level 2 heat alert is in place for the South West, with the Met Office also issuing a weather yellow to take effect on Sunday July 17, when temperatures could reach the low -30s.
Dorset and Wiltshire Fire and Rescue team manager Brad Stevens said: “While the sunshine is very welcome after the recent rain, it does mean an increased risk of fires starting.
“If you’re visiting our ruins, woodlands or countryside, please avoid making a fire and bring a picnic, not a barbecue – a few simple steps can make all the difference.”
He added: “We would also remind people to be careful if they have a barbecue or fire at home.
“Too often, we see property destroyed when an initially small fire suddenly gets out of control. Never leave a fire or barbecue unattended and place it well away from fences, trees or buildings.”
