Police are searching for two men who were seen running away from the scene of a fatal stabbing.
Fahad Mohamed Nur, 18, was stabbed near Cathays train station in Cardiff at about 00:30 BST on Sunday.
He was taken to the city’s University Hospital of Wales where he died from his injuries.
Police have released CCTV footage of two men running away from the area and a picture of a baseball cap they believe one of the men was wearing.
In a tribute, Mr Nur’s family said “the hole left in their heart will never be filled”.
The CCTV footage shows two men running from the lane, between Corbett Road and Park Place, where Mr Nur was found.
They then make their way past taxis and people.
Fahad Mohamed Nur died in hospital after being attacked near a railway station
Det Ch Insp Mark O’Shea said: “From the footage we can see there are a large number of potential witnesses in the area and vehicles, including taxis, driving up Park Place.
“Fahad comes from a loving family who are devastated by what has happened, and their grief is shared by the wider Somali community who are proving to be an invaluable support.”
A photograph of a “distinctive” baseball cap found near the National Museum of Wales on Park Place, which police believe one of the men was wearing, was also released.
Two men, aged 18 and 19, were arrested in connection with the incident but have since been released with no further action.
Mr Nur’s family, who live in Cardiff, are being supported by specially trained officers.
South Wales Police want to speak to the two men seen running near the scene
A baseball cap was found near the scene
In a statement, they said: “There will never be anyone like Fahad.
“He was very giving and loving to his friends and family. He was always the person to make you laugh and was known as the class clown.”
Mr Nur’s brother said: “As a brother we were very close. I love him so much.”
His father added: “I miss him greatly and I will never be the same.”