A large number of Armed Police have surrounded an address in Yarnbrook tonight (Tuesday) as the National Police Air Service helicopter circles in the skies above.
4 Armed Response Vehicles are currently present at West Ashton Road & Westbury Road having responded to the area sometime around 22:00.
The NPAS helicopter is focusing its aerial search on the Clanger Woods area, where a number of Police units are also present on the ground. 
It is currently unclear what has prompted the major response.
UPDATE @ 22:56 – Wiltshire 999s has been told that police have surrounded an individual property with their guns drawn.
The NPAS helicopter based out of Filton has departed the scene having spent over 45 minutes circling the area.
