Enquiries into the case continue and detectives are still appealing to the public for information.
Officers were called to a shop in Carr Road, Walthamstow, by London Ambulance Service at 21:10hrs on Sunday, (April 17) following reports of a stabbing.
When they arrived they found the 70-year-old victim suffering from serious stab injuries.
The shopkeeper was taken to hospital by London Ambulance Service, where he remains in a serious but stable condition.
CCTV footage showed the shopkeeper being attacked by the three males as he tried to defend himself while they attempted to rob the store.
The victim’s wife and two customers were also in the store during the incident.
Three suspects were seen to leave the premises immediately after the stabbing.
They are described as three white males aged in their twenties all wearing dark tracksuit bottoms and dark jackets with hoods.
One man had a grey hooded top underneath a black puffa-style jacket.
Detective Sergeant Ben Voss of Waltham Forest CID said: “This was a violent attack on a pensioner who was trying to run his shop.
“The assailants used an extreme level of violence against elderly man who was trying to defend himself, his wife, customers and business.
“The attack could have resulted in tragic consequences but luckily the victim is now recovering in hospital.