Investigators released no other details on Friday's incident where Maria Mitousis, who specializes in family law, was hurt by a suspected explosive device that was sent to the office where she worked.
Police say they are still at the scene, and that the 38-year-old victim remains in hospital after being taken there in critical condition.
One source who spoke to The Canadian Press on condition of anonymity said Mitousis lost a hand and was in danger of losing the other one.
A GoFundMe page has been set up online to raise money for Mitousis, stating she "sustained very serious injuries" and "will require financial support as she recovers from this horrific event."
Police are asking anyone with information about the case to contact them.
Police Supt. Danny Smyth told reporters Friday that investigators don't believe the incident was an attack on the justice system.
They said the victim was alone in the offices of the small firm — Petersen King — at the time of the blast and that nearby residents alerted them.
After the blast, police went to the downtown law firm where she had worked until last fall — Monk Goodwin — and workers were removed as a precaution.
Police said they were called there for a report of a suspicious package, but that it turned out to be unfounded.
Mitousis's boyfriend, Barry Gorlick, had worked at Monk Goodwin before being disbarred Monday on 15 counts of professional misconduct.
Smyth said police "were aware" of the connection to Gorlick and media coverage of his misdeeds, but stressed they had no suspects and no motive yet for the bombing.
Note to readers: This is a corrected story. An earlier version misspelled the law firmSuggest a correction