Cassie Hayes, 28, was attacked as she worked her shift at the Tui branch in Southport town centre on Saturday, with officers from Merseyside Police called to the scene in Chapel Street at 1.25pm.
Shocked shoppers looked on as emergency services - including two air ambulances - rushed to try to save the mother-of-one.
Ms Hayes, who lived in the Southport area, was taken to hospital, where she died from her injuries.
A post-mortem showed the cause of death was shock and haemorrhaging as a result of a wound to her throat, police said.
Tributes have been paid to a "a lovely person" who had an "absolute heart of gold".
Former colleague Gordon Campbell, 44, from Preston, said he would remember her "mischievous" sense of humour.
He said she was "happy, full of love and... had an absolute heart of gold. She will be most definitely missed by everybody that knew her."
Another former colleague wrote on Facebook: "Such sad news about Cassie, worked with her a few times when I was working for Tui and she was such a lovely person. Thoughts are with all my friends at Tui, Tui Southport and her family and friends. RIP Cassie xxx."
A police cordon remains around the area and a handful of bouquets have been laid outside Tui after being handed to officers.
Police are questioning a 30-year-old man from the St Helens area on suspicion of murder.
Officers said the incident is believed to have been domestic-related.
Ms Hayes' ex-partner, Leah McDonald, said on Facebook she was "heartbroken and numb".
She posted: "What can I say. This girl was my absolute world from the first moment we met on 4 July 2007 till this very day.
"We had our fall outs, our ups and downs but I can tell you now despite all that we absolutely loved each other and out of all the people in the world I could not of picked a better mammy for our child.
"She's my gem, my best mate. Even when we split she was there for me… this girl has been my rock and the most amazing mammy. I am heartbroken and numb. How could anyone do this to my cassie."
Ms Hayes' former boss, Michael Richards, wrote on Twitter: "To all who knew our AMAZING Cassie. I was lucky enough to of been her manager at Thomson (Tui) Southport. She made me laugh, cry and enjoy going to work every day and be in her company. She is one of life's good ones."
Travel Gossip, an online community of travel professionals, has set up a fundraising page for Ms Hayes on Go Fund Me.
Detectives are appealing for anyone with information to contact Merseyside Police on 101 quoting log 470 of 13 January or the Crimestoppers line anonymously on 0800 555 111.
