One person is in a serious condition after hydrogen sulphide leaked from a truck and trailer unit at a Taieri industrial park.

Silverstream Industrial Park on Dukes Rd has been cordoned off by police with firefighters also at the scene.

One person was listed as critical but their condition has been downgraded to serious, a Hate Hone St John spokesman said.

Fire crews are working to contain the leak, a Fire and Emergency spokeswoman said.

Two ambulances have been at the site and one has left.

Workers have been seen leaving Silverstream Industrial Park on Dukes Rd and are gathering outside.

One told the ODT he had been asked to evacuate.

A fire engine can be seen inside the industrial park.

More to come