Emergency services were called to Farmhouse Biscuits, Nelson, this afternoon.
Police and the North West Air Ambulance were at the factory, at the junction of Brook Street and Chapelhouse Road, but the nature of their visit has not yet been released. Speculation on social media sites has included a joiner working at the site being involved in a serious fall.
The air ambulance landed on the Chapelhouse Road car park but it is not known whether anyone was taken to hospital from there.
A company spokesman said managers were in meetings and not available for comment.
Further details will appear here later.