Anthony Ferrie, 33, left one guard unconscious and injured the other’s arm before jumping from the van. He had been returning to prison from a visit to St John’s Hospital in Livingston at around 1pm.
Police have confirmed they have launched a search for Ferrie, a prisoner from HMP Addiewell, while the two guards are being treated for their injuries in hospital.
Ferrie is described as white, 6 ft tall, of slim build and is wearing a blue sweater, jeans and trainers. He has links to Bellshill, Motherwell and Grangemouth.
Willie Galloway, head of operations for G4S’s custody transport in Scotland, said: “During a prisoner transport movement at approximately 1pm today, a prisoner escaped custody at St John’s Hospital in Livingston.
“Two members of our crew were injured during the incident which left one unconscious and the other with an injury to their arm.
“While they both remain in hospital, their injuries do not at this stage appear to be life threatening and we are supporting them and their families.
“We are assisting Police Scotland’s enquiry to recapture this prisoner and are working with the Scottish Prison Service to understand the events leading up to this escape.”