Niagara Health says approximately 22 people are expected to require treatment following a chemical spill in St. Catharines Tuesday morning.

St. Catharines Fire Chief Dave Upper says crews responded to THK Rhythm Automotive Canada Ltd. shortly after 10:30 a.m. for reports of a workplace incident.

Upper says a third-party contractor accidently hit a valve open, spilling five litres of hydrochloric acid. Multiple staff members were exposed to the liquid chemical as it vaporized in a large, open space.

Several workers who were close to the spill were able to turn off the valve.

Niagara EMS spokesperson Bryce Brunarski says three people were directly exposed. In order to be cautious, affected staff used their in-house decontamination showers and were taken to hospital.

Paramedics brought nine others with minor exposure to hospital. Ten asymptomatic people with limited exposure were sent to hospital on a St. Catharines city bus.

Upper says all of the liquid and vapor has been contained inside of the facility, meaning there is no risk to the public.

The Ministry of Labour and Ministry of the Environment have been contacted.

Upper says a remediation hazmat crew has been called to the scene.