A Mississauga, Ont. woman has been charged with first-degree murder in connection with the death of her two-year-old son.

Police were called to an apartment building on Sherobee Drive in Mississauga at approximately 2:30 p.m. on Monday.

Officers told CTV Toronto's Tamara Cherry that the woman had called 911 saying that someone was hurt.

When they arrived, they located the body of a two-year-old boy inside an apartment, police said. The toddler had "obvious signs of physical trauma to his body," officers said in a statement Tuesday. He was later identified as Surfeal Okubazgi.

The boy's 27-year-old mother was arrested at the scene. On Tuesday, police announced that Russom Tesfamar Yordanos has been charged with first-degree murder.

Police allege that the boy was killed in the apartment. They said the boy was left in the apartment and that the woman brought her six-month-old daughter to the building's lobby to wait for an ambulance.

Officers said the child's father lives in the apartment, but was not home at the time.

Investigators are looking into whether Yordanos suffered from postpartum depression. Regardless, the charge will remain and it will be up to the court to decide how to proceed if mental illness was a factor, Insp. Sean Lawson said.

Yordanos appeared briefly in Brampton court on Tuesday, speaking only to say her name and date of birth. She was remanded into custody, and will reappear in court on Wednesday.

The woman's lawyer, Gary Batasar, said the woman is "very shaken by what's going on."

Speaking to reporters outside the courtroom, Batasar said the charges were very unusual, but would not provide further details in the case.

"This is the very beginning of the case, she's presumed innocent until proven guilty, and we'll see where the chips fall when they may," he said.

"Postpartum depression does not fit within the confines of laying a first-degree murder charge. I suspect as the matter travels through the court system, it will not be a first-degree murder charge," he added.

Anyone with more information is asked to contact investigators at 905-453-2121, ext. 3205, or call Crime Stoppers anonymously at 1-800-222-8477 (TIPS).