Police were called to a St Asaph St house in central Christchurch this afternoon to investigate after probation officers experienced burning throats and vomiting after leaving the property.
Fire Service spokesperson Steve Kennedy says the two workers have been given a decontamination shower, and taken to hospital as a precaution for further checks and monitoring.
He says They are suffering a possible chemical or allergic reaction and both have a rash and breathing difficulties.
Police are also investigating a Kainga property, the officers visited earlier in the day.
Police are trying to establish what sort of drug or chemical the probation officers have been exposed to.
Firefighters in HazChem suits have been seen entering the Probation Office on Ensors Road where the two probation officers returned to.
The door of the office has been sealed off.
It's still unclear what the substance is.
A Corrections spokesperson says emergency services are currently at the Ensors Road Community Corrections site after two probation officers became unwell this afternoon.
Staff remain at the site, and Fire and Emergency New Zealand are investigating, the spokesperson said.
"Our focus is on supporting the wellbeing of our people."