A man is in a life-threatening condition in hospital after he was stabbed twice in the chest.
He collapsed on the floor and police were quickly called.
On arrival officers found the victim lying behind the counter with what appeared to be two puncture wounds and he was drifting in and out of consciousness.
Officers quickly provided first aid by sealing up the wounds and providing oxygen, as he lay there breathing but non-responsive.
The man appears to have been stabbed on a nearby street, and then stumbled into the shop.
A scene remains in place at the shop and the potential site of the attack, on Mansfield Street near the junction with Peel Street, as detectives continue their investigations.
The man remains in a serious condition in hospital, where he has already undergone surgery.
Detective Sergeant Louise Bradford, from Nottinghamshire Police, said: “The victim has stumbled into the shop after suffering two life threatening stab wounds, in an attack believed to have occurred further up Mansfield Road.
“Officers quickly provided first aid at the scene to stem the bleeding, but he is still in a critical condition in hospital.
“Our focus is to establish what has happened to the victim before he managed to get to the takeaway for help.
“Officers are in the area working with local residents and businesses to gather information, retrieve vital CCTV footage and provide reassurance to those living and working locally.
“We take knife crime extremely seriously and are committed to stopping those that carry knives and offensive weapons.
She added detectives are keen to track down and speak to anyone who may have been in the area in the early hours of this morning, and are appealing for witnesses to come forward.
Anyone who may have information or has any CCTV or dashcam footage is urged to contact the force by calling 101, quoting incident 73 of 11th September 2021. Alternatively people can call Crimestoppers anonymously on 0800 555 111.