TORONTO — The man accused of shooting 15 people and killing two on a busy, restaurant-filled Toronto street struggled with severe mental illness, his family said in a statement late on Monday as police sought a motive in the shooting spree.

Less than a day after two young women, ages 10 and 18, were killed and 13 other people were wounded by a gunman, the suspect was identified by the independent Special Investigations Unit (SIU) as Faisal Hussain, a 29-year-old Toronto resident. He was found dead shortly after the shooting, authorities said.

"We do not know why this happened," Toronto Police Chief Mark Saunders told reporters on Monday, adding that he would not speculate about the gunman's motive. "It's way too early to rule out anything."

The suspect, armed with a handgun, opened fire at 10 pm EDT on Sunday on a stretch of Danforth Avenue filled with restaurants and family-friendly attractions in the city's Greektown neighborhood, the SIU said.

"We are utterly devastated by the incomprehensible news that our son was responsible for the senseless violence and loss of life," Hussain's family wrote in a statement, adding that he suffered from severe mental illness as well as from "psychosis and depression his entire life".

"While we did our best to seek help for him throughout his life of struggle and pain, we could never imagine that this would be his devastating and destructive end," the statement said.

Police did not identify the two young women killed in the shooting spree. A local politician, Nathaniel Erskine-Smith, confirmed the 18-year-old victim was Reese Fallon, a recent high school graduate who planned to study nursing.

"The family is devastated," Erskine-Smith said in a statement, adding that they have asked for privacy while they mourn a young woman who was "smart, passionate and full of energy".

The gunman exchanged fire with police, fled and was later found dead, according to the SIU, which investigates deaths and injuries involving police.

The suspect had a gunshot wound, authorities said, but would not elaborate on the circumstances or cause of his death. An autopsy on the suspect will be conducted on Tuesday, SIU spokeswoman Monica Hudon said.

Hours after the fatal shooting, in an apparently unrelated incident, a man with a knife was arrested during a military ceremony on Parliament Hill in Canada's capital, Ottawa. The Defense Ministry said no one was injured and gave no further details.

Prime Minister Justin Trudeau wrote on Twitter on Monday: "The people of Toronto are strong, resilient and brave — and we'll be there to support you through this difficult time."

Toronto Mayor John Tory told reporters the city has a gun problem, with weapons too readily available to too many people.

"Why does anyone in this city need to have a gun at all?" he asked in an address to city councilors early on Monday.

Bill Blair, Canada's newly appointed minister of border security and organized crime, who has been given the job of tackling gun violence, met with Tory on Monday afternoon.

REUTERS