A chemical spill at a Clarington plant that specializes in safe handling of dangerous goods sent two employees to hospital Thursday afternoon.

A large cloud of yellow smoke could be spotted from Highway 401, coming from the Detox Environmental facility on Bennett Road.

According to Durham Regional Police, the smoke cloud was released after a tanker containing a nitrous oxide came into contact with another chemical.

The reaction sent a cloud of gas into the building and into the air outside the building.

About 12 Detox employees were forced to leave the building, as were the employees of a nearby forklift company, police said.

Two Detox employees who inhaled the chemicals and were taken to Bowmanville Hospital.

One of the employees had serious injuries, police said.

The Ministry of Labour has been called to investigate the incident.