Police turned out in large numbers along with paramedics from Yorkshire Ambulance Service at around 2.20pm.
A Yorkshire Air Ambulance helicopter also attended the scene of the incident Lingwell Nook Lane in the Lofthouse area.
Reave Westwell, who lives on the street, said: "I saw the ambulance first responders speed past. The air ambulance was circling and landed in the field.
"At one point there were three ambulances and nine police cars. They went into a house at the end of the road.
"All the neighbours were coming out and looking."
She described seeing armed response officers and police dogs being involved in the response.
The number of emergency service vehicles at the scene has now reduced, although police are standing guard outside the house.
A Yorkshire Ambulance Service spokeswoman confirmed its teams were attending an incident but was unable to give details at this stage.
More to follow