Faisal Hussain, the 29-year-old man responsible for the mass shooting on the Danforth this weekend, was known to police for his previous “online activity,” the Toronto police say.

There has been no word on the type of online activity the police knew about or how long ago it happened.

Hussain fired multiple shots along the Danforth on Sunday night, killing 18-year-old Reese Fallon as well as a 10-year-old girl. Thirteen others were injured in the mass shooting that started outside a restaurant at Danforth and Logan avenues in the heart of Greektown.

A motive for the shooting is not yet known but in a statement released on Monday, his family said he suffered from “severe mental health challenges” and had struggled with psychosis and depression his entire life.

Hussain died from a gunshot wound, but it’s not yet clear if it was self-inflicted or the result of an exchange of gunfire with police.

The province’s Special Investigations Unit (SIU) said it is probing the circumstances surrounding his death. An autopsy is scheduled for Tuesday morning.

SIU spokesperson Monica Hudon said the shooter was involved in a brief exchange of gunfire with two Toronto police officers on Bowden Street, just south of Danforth Avenue.

“He was found deceased (on Danforth Ave.) after the interaction,” she confirmed.

Police executed a search warrant on Monday at an apartment in the Thorncliffe Park Drive area as part of their investigation.