A shopkeeper was hit over the head by a robber armed with a stone after he came behind the counter demanding money.
The offender entered the General Store on Spencer Street in Accrington at around 1.30pm on Thursday, August 2.
Police said he hit the male shopkeeper over the head with the stone before demanding that he open up the till.
However when the victim refused the offender fled the store empty handed.
Officers said the shopkeeper was taken to hospital for treatment on a head injury.
No arrests have been made.
The offender is described as white, around 6ft tall with a slim build, in his 20s with short grey hair.
He was wearing a blue hoodie and grey shorts.
Anyone with information call Lancashire Police on 101 quoting log number 715 of August 2.