The robbery occured at around 1100 on Monday 16th outside a branch of Lloyds TSB on Birmingham Road, Sutton Coldfield, West Midlands Police said.
The security officer was taken to hospital for treatment to a gunshot wound to the officers leg. Police said he grappled with his attacker before he was shot.
Group 4 Securicor have offered a £50,000 reward for information leading to a conviction after yet another of it's employees gets injured in the line of duty.
The man escaped with an accomplice in a silver Honda car but Police have not said how much money was taken in the raid.
Det Ch Insp Chris Pretty, of West Midlands Police, said the security officer had suffered a serious injury but was in a stable condition in hospital.