A 29-year-old woman who was stabbed at a Toronto law office has died in hospital and a 33-year-old man in custody now stands accused of her murder, police say.

Just before 2 p.m. on Thursday, police said two males entered 238 King Street East, the offices of Hicks Adams LLP, a law firm specializing in criminal defence.

A woman, now identified as Julia Ferguson, suffered a critical stab wound and was rushed to a hospital trauma centre without vital signs.

A GoFundMe set up by Ferguson's friends says she worked as a receptionist at Hicks Adams and "was attacked and stabbed in the chest."

"The stab wound to her chest resulted in a puncture wound to her heart leaving her without vital signs upon paramedics arrival, some friends wrote on the GoFundMe page. "Due to Julia’s strength the paramedics were able to resuscitate her and she was rushed to the hospital."

They said Ferguson suffered oxygen loss due to her attack, which made recovery unlikely.

On Sunday, Ferguson was taken off life support and died in hospital.

"She leaves behind a mother, brother, boyfriend, family and many friends who will miss her dearly," the GoFundMe message says. "If you were blessed to know Julia you know what a beautiful and kind hearted soul she was."

Police said a suspect fled the scene and later surrendered to police.

He was identified on Monday as Osman Osman of Toronto.

"This attack was not random," Det. Sgt. Tiffany Castell said Monday while updating the investigation. 

Castell said the suspect was targeting the business during the attack and not Ferguson. 

"The business itself was certainly the target," she said. 

Castell would not reveal any other information about what could have led to the stabbing. 

Osman was initially charged with aggravated assault and attempted murder, and investigators say those charges will be upgraded due to Ferguson’s death.

She is Toronto's 55th homicide victim of the year.