Detectvives have arrested a St Helens man on suspicion of murder after a woman was attacked at a travel agents earlier today.
Police sealed off Chapel Street in Southport after a serious incident at a branch of Tui at around 1.25pm.
One woman, aged 26, was taken to hospital, where she later died of her injuries.
Tonight she has been named by police as Cassie Hayes, who was from the Southport area.
Detectives have also confirmed that a 30-year-old man from the St Helens area has been arrested on suspicion of murder.
He is currently being held for questioning at an undisclosed police station on Merseyside.
The incident is believed to be of a domestic nature but no further details have been revealed.
The victim is thought to have been attacked in front of colleagues at the branch. She was later stretchered away to a waiting ambulance.
Police placed a cordon around the store so that forensic investigators could comb the scene.
A spokeswoman for Merseyside Police said: "We can confirm a murder investigation has been launched following an incident in Southport today.
"Detectives are appealing for anyone with information to contact Merseyside Police on 101 quoting log 470 of January 13 or the Crimestoppers line anonymously on 0800 555 111."
Later the woman's bosses at Tui confirmed it was one of their colleagues who had lost her life.
A Tui spokeswoman said: "We regret to confirm that a female member of staff at our Southport Tui retail store tragically died in an incident today.
"We send our deepest sympathies to the friends and family of the staff member involved.
"We're doing everything possible to assist the local police with their investigation and support our customers and staff at this difficult time."