Police officers were called to a Sheffield supermarket after a knife was seen during a disturbance involving two men.
South Yorkshire Police said the alarm was raised after a knife was spotted during a dispute between two men at Tesco Extra on Savile Street, Burngreave.
One man is said to have lifted up his top during the row, showing the handle to what is believed to have been a knife during the incident at 9pm on Tuesday, June 27.
Officers searched the area for the suspect but he had disappeared.
He was around 5ft 8ins tall, slim and was wearing a camel coloured V-necked jumper and jeans.
The incident is not being linked to incidents of violence in Burngreave during which one man was shot and a teenage boy was stabbed.
A special police team has been deployed to the city suburb in the wake of the recent clashes.
A South Yorkshire Police spokeswoman said: "Police responded to reports of a suspected sighting of a knife at Tesco Extra, Savile Street, Sheffield.
"It was reported during a dispute between two men in the store, one of the men had lifted his top to show the handle of what is thought to have been a knife.
"The man then pulled his top back down and left the store.
"Officers conducted a thorough search of the area at the time of the incident. No knife was recovered.
"The incident is being investigated and enquiries are ongoing in the area."
Anyone with information should call South Yorkshire Police on 101.