A masked man threatened a family at gunpoint after forcing his way into their North Lanarkshire home as two children were sleeping upstairs.
The incident happened in Garfield Avenue, Bellshill, at 21:30 on Friday.
A couple aged 60 and 58 were at home when the gunman knocked on their door before entering.
Police said "an altercation" followed and the man only fled when the couple's daughter and her partner, who had been upstairs, came down to help.
The gunman, who was wearing a black balaclava, made off along Garfield Avenue and onto Garfield Drive. He was last seen in Orbiston Drive.
One line of police inquiry is that the incident may have been a case of mistaken identity.
Det Sgt Lorraine Wilson, from Wishaw CID, said: "This man barged into a home where two young children were asleep upstairs and threatened the occupants with a firearm.
"Thankfully nobody was injured but it is absolutely vital that we trace this reckless individual and extensive inquiries are ongoing to establish the full circumstances surrounding the incident.
"At this time we have no information to suggest why this home was targeted, and the possibility of mistaken identity is a line of inquiry.
"It would still have been daylight at the time of the incident and I would appeal to anyone who was in the area and may have noticed a man dressed in black acting suspiciously to please get in touch."