FRESNO, Calif. (AP) — Authorities say they have fixed an ammonia leak that sickened workers at a Fresno winery, but the area remains cordoned off.

Fresno Fire spokesman Sean Johnson says investigators determined that a pipe was the source of Thursday's leak at the Golden State Vintners plant.

Officials say 10 workers were treated for ammonia exposure after the leak created a vapor cloud. Three were taken to a local hospital.

Johnson says the Fresno winery is in an agricultural area, so there are no homes within the 1-mile evacuation zone. Residents nearby have been advised to stay indoors, turn off their air conditioners and keep their windows closed.

Last month, an employee at another winery in Sanger died after being exposed to ammonia, which is used as a cooling agent.