The victim’s son believes the bandits are connected with a previous robbery on the Cignall tobacconist on Miller St, Thornbury.
Kevin Zhu said his father Paul, 60, tried to defend himself as four or five thugs converged on the store wielding a block-splitting hammer at 11.50am.
He said their knowledge of exactly where to find the store’s smoke stockpile indicated they were connected to a robbery on the shop in November, or had knowledge gleaned from that crime.
“They’d definitely been here before because they knew where everything was,” Mr Zhu said.
“Basically, they knew things they shouldn’t have. We don’t show people where our storehouse is.”
Police said the gang stole cigarettes before fleeing in a BMW, leaving Mr Zhu with facial injuries.
He is recovering in hospital.