UPDATE 10/12/11 @ 8:35 a.m.
CATLETTSBURG, Ky. (WSAZ) -- Three workers were sent to the hospital after being exposed to hydrofluoric acid at the Marathon Refinery in Catlettsburg.

Marathon Spokesperson, Shane Pochard tells WSAZ.com the incident happened at 10:15 Tuesday night while contract workers were doing maintenance work in the Alky Unit at the refinery.

Pochard says a total of four workers were exposed to what he called a small “vapor cloud” that was created by a mixture of the acid vapor and rain water.

He says three of the workers were taken to a local hospital where they were treated and released. A fourth worker was treated at the scene.

Boyd County 911 tells WSAZ.com an ambulance was dispatched to the refinery about 11 Tuesday night.

They say one person was then transported to King's Daughters Medical Center.

There is no word yet on the reason behind the transport.

WSAZ has contacted the refinery multiple times to get answers about what happened, but no details are being released at this time.

Keep clicking on WSAZ.com for the latest information.