Detectives in Derry are investigating an incident at a flat on Monday night.
The PSNI said they received a report around 11:25pm on June 29 that a male, brandishing a suspected firearm, arrived at a property on the Abercorn Road area and tried to force his way inside.
It is understood that the man may have been accompanied by a second male.
The male occupant was able to stop the man from getting inside the flat, who then made off.
The male, who tried to force his way inside the property, is described as being aged between 20 and 30-years-old, of a slim/skinny build and is thought to be around 5'9'' tall and wore a dark beanie hat, a dark-coloured hooded top and bottoms.
Meanwhile, the male also had his mouth and nose covered with what was described as a dark-coloured snood.
No injuries were reported during the incident.
Detective Sergeant Lizzie Ballentine said: "Our enquiries into this incident are continuing, and we would appeal to anyone who may have been in the area and saw any suspicious activity, including any individuals, or any vehicles being driven in a suspicious manner, to get in touch with detectives at Strand Road by calling 101, and quoting reference number 2102 of 29/06/20."
You can also submit a report online using our non-emergency reporting form via http://www.psni.police.uk/makeareport/. Crimestoppers can be contactedanonymously on 0800 555 111 or online at http://crimestoppers-uk.org/
