A teenager is in a serious condition in hospital after being stabbed as he walked along a street.
Police believe the 16-year-old was attacked by a man who got off a bus at Main Street in Blantyre, Lanarkshire, at about 2300 BST on Friday.
The victim was taken by ambulance to Hairmyres Hospital in East Kilbride where staff described his condition as "serious but stable".
The attacker, who had short brown hair, fled the scene in an unknown direction.
Strathclyde Police said they were also keen to trace a woman who was seen walking beside the teenager and his friend at the time of the attack.
Det Con Neil Wilson said officers were trying to establish a motive for the attack.
He added: "At this time, we are still trying to trace the girl who was in the company of the victim when he was attacked.
"She is described as white, around 24-years-old, with long brown hair and was wearing a cream jacket and a denim skirt.
"We believe that she may hold vital information which could assist us and I would appeal directly to her to come forward to police."
The force said they were also investigating whether a man walking a dog, who appeared to deliberately bump into the teenager in the street prior to the attack, was connected with the incident.
Mr Wilson added: "He is believed to be around 19-years-old, approximately 5ft 9ins in height and of medium build."
Police believe the man suspected of carrying out the stabbing may have been travelling on the 201 or 263 bus from Hamilton to Blantyre.
They have urged anyone with information to get in touch.