More than 40 people exposed to carbon monoxide in a greenhouse in Delta, B.C., on Saturday were taken to hospital.

B.C. Emergency Health Services said 13 ambulances responded to the incident. Thirty-two people were in stable condition and 10 in "serious to critical" condition.

The incident happened at Windset Farms in the Ladner area, according to the Delta Fire Department.

Update: major incident in Delta was at a farm where there was exposure to carbon monoxide. <br><br>13 ambulances responded to a major incident in Delta. More than 40 patients have been transported to hospital - 32 in stable condition, 10 in serious to critical condition. —@BC_EHS

Deputy Chief Guy McKintuck said it appears combustion-powered pressure washers being used in an insufficiently ventilated area.

"[Our crews] weren't sure what it was at first, but through their investigation, they quickly realized that it was a carbon monoxide incident and they acted accordingly," McKintuck said.

WorkSafeBC confirmed it is investigating.

Carbon monoxide — sometimes referred to as CO — is a colourless, odourless gas released as a byproduct of incomplete combustion, toxic to humans and most other animals. CO exposure can cause headaches, nausea, vomiting, dizziness and disorientation, and eventually death.