FIREFIGHTERS battled to rescue cattle from a burning barn.

Crews were forced to stand back and let the fire burn out at Knightstone Farm, near Ottery St Mary when they discovered five tonnes of potentially explosive fertiliser was stored inside.

It is not yet known what caused the fire which was spotted at about 8pm, on Monday night.

Firefighters freed 29 of the 30 cattle that were inside the barn but one died.

Fire engines from across the area were sent to the blaze.

Crews, who were told the barn contained three tonnes of ammonium nitrate fertiliser and a pallet of caustic soda, set up a 200m safety zone around the building.

Police were called and residents of nearby buildings were informed.

Exmouth group commander Chris Bridgeman, who was in charge of the incident, said: "The fire affected the whole building. Apart from 30 cattle, there were 100 tonnes of straw and hay inside as well as the hazardous materials.

"The fertiliser can give off toxic fumes and is explosive. We had to let it burn out in a controlled way.

"The roof fell in and the flames were 20 to 30ft high."

He said the Environment Agency was also concerned about run-off water polluting the area.

Overhead power cables were also thought to be affected by the fire. Crews were still at the scene at 4pm yesterday.

Knightstone Livestock Enterprises is a family-run farm business. It is owned by Richard Lawrence of Godford Farm, in Awliscombe.

Yesterday he did not want to comment on the incident.

The farm is understood to be home to Vicki Thomas and her fiancee, Dave, who are both heavily involved with Honiton and Axminster Young Farmers clubs.