A chemical scare at a Waterloo auto parts plant, Ultra Manufacturing. The plant was evacuated and shut down for more than four hours, this after a cloud of noxious gas was released on the production floor. The chemical indentified late this afternoon by fire fighters as formaldehyde.

The incident happened around eight this morning but the alarm that summoned emergency crews wasn't sounded until about two hours later.

The company President and CEO says Joe D'Angelo says there was a problem on the production line. "What we gather is that two incompatible materials were loaded into a machine and then that created a release of an odour or a vapour and the employees in the immediate area were affected by that." 

Four workers were sent to hospital by cab and then about two hours later, emergency crews were called in.   More people were reporting illness causing officials to evacuate the building. 

Waterloo fire department Chief, Richard Hepditch says “several people had been sent to hospital as a result of inhalation of a chemical which we believe to be formaldehyde."

Eight workers were treated at hospital, while others were assessed at the scene, for nausea, headaches and tearing eyes. The ambulance people triaged approximately forty people who were complaining of symptoms” says Hepditch.

A few hours the incident, initial testing had showed the air was clear, but Waterloo fire department called in some specialized equipment to make sure it was safe. "Obviously the most important thing we want to make sure our people are going to be okay" says D'Angelo.

At about 2 in the afternoon, about six hours after it all began firefighters suited up and entered the manufacturing part of the plant.  A few minutes later, the all clear was sounded.

The investigation has been handed over to the ministry of labour.