Five people, including two firefighters, were taken to hospital earlier, after a reported chemical spill at an industrial site in County Armagh on Friday.
The Northern Ireland Fire Service (NIFRS) got at a call at about 22:30 BST on Friday about the incident at Leprino, a cheese factory, in Steps Road near Magheralin.
Seventeen people were assessed at the scene by ambulance services, with five being transferred to hospital.
All have since been discharged and none of their conditions was described as life-threatening.
Four fire appliances and a Command Support Unit attended the scene along with a number of emergency ambulances, a Hazardous Area Response Team, a doctor and PSNI.
The fire service said the incident was brought under control as all emergency services left the scene at 04:50 BST.
There is no risk to the public, but the fire service has asked that people avoid the area.
A precautionary 100-metre exclusion zone was implemented.