A 20-year-old man has been arrested on suspicion of murder after a couple were found dead on a Cardiff street, yards from the shop where they worked.
Zoe Morgan, 21, and Lee Simmons, 33, were found with stab wounds at about 05:50 BST on Queen Street, close to Matalan.
Police believe the man, from Castleton, Newport, was known to them and officers are not looking for anyone else.
Both victims are from Cardiff and their families have been informed.
Mr Simmons, of Grangetown, worked as a sales assistant and had been in a relationship with Miss Morgan since July.
It is understood Miss Morgan, of Llandaff North, had studied fashion at the University of South Wales before starting work as a visual merchandiser at Matalan in June.
A university spokeswoman said: "We are deeply saddened to learn of the loss of Zoe, who had been a popular and well-liked student who was now doing well in her chosen career.
"Our thoughts are with her family as we come together, as a close-knit university community, to support our students and colleagues who knew Zoe during her time with us."
Melanie Davidson, Miss Morgan's manager at McDonald's where she worked for several years until she graduated, said she was "heartbroken" by the news.
"I've never met such a kind, caring, sweet, loving and funny girl in all my 22 years of employment," she said.
"She was beautiful, not just on the outside but on the inside."
The arrested man, who remains in custody at Cardiff Bay police station, was detained at an address in Castleton within an hour of the bodies being discovered.
Matalan chief executive Jason Hargreaves said: "Both of the victims worked at our Cardiff branch so understandably all of our colleagues are receiving our full support.
"We extend our condolences to the families of everyone involved."
The store remains closed and is due to reopen on Thursday.
A post-mortem examination will be carried out on Miss Morgan and Mr Simmons.
South Wales Police Ch Supt Belinda Davies said: "This incident occurred in the main shopping area in the heart of the city in rush hour and it has no doubt shocked the community of Cardiff.
"We are in the very early stages of the investigation but I would like to add that at this stage we believe the suspect was known to the victims and it was not a random assault.
"I would like to dispel speculation circulating as to the motive behind this tragic incident and make it clear that this is not being linked to terrorism and any links to the homeless community are unfounded."
Queen Street was reopened by 12:50 - police activity had been focused close to Boots on the busy shopping street.
A spokesman for the shop said: "We're deeply shocked and saddened by the incident that took place on Queen Street this morning and our thoughts are with the families affected."
St David's shopping centre, which partially adjoins Queen Street, was open to shoppers, but some entrances were affected while investigations continue.
One man, who was staying at a nearby hotel, said: "I saw somebody lying outside Boots and paramedics giving them chest compressions. It was not something you want to see ever."
There were at least seven police vehicles at the scene when forensics officers conducted their investigation.