OTTAWA -- Six people from Sri Lanka, including a mother and four young children, were knifed to death in the Canadian capital Ottawa late on Wednesday, police said on Thursday, rocking a country where mass murders are rare.

Prime Minister Justin Trudeau said he was horrified by what he called a "terrible tragedy." The father of the family was also wounded in the attack and is in hospital.

Police said Febrio De-Zoysa, a 19-year-old male student from Sri Lanka, had been arrested and charged with six counts of first degree murder and one count of attempted murder. De-Zoysa knew the family and had been living in the house, they said.

The victims killed were a 35-year-old woman and her children aged 7, 4, 2 and 2 months, as well as a 40-year-old man who was an acquaintance of the family.

"This was a senseless act of violence perpetrated on purely innocent people," Ottawa police chief Eric Stubbs told a televised news conference. Police said they had had no previous dealings with the suspect or the family.

Ottawa Mayor Mark Sutcliffe, in a social media post, said it was "one of the most shocking incidents of violence in our city's history".

Ottawa, which has a population of one million, saw 14 murders in 2023 and 15 in 2022.

Wednesday's victims were found inside a house in the southwestern suburb of Barrhaven. Police arrived on the scene following emergency calls shortly before 11 p.m. on Wednesday.

Mass killings in Canada are infrequent. In December 2022, a man shot five people in a Toronto suburb before being gunned down by police.

In September that year, a man stabbed and killed 11 people in the western province of Saskatchewan. He died of a cocaine overdose shortly after being arrested.

An emergency responder leaves the home where four children and two adults were found dead inside in the Ottawa suburb of Barrhaven, Ontario, Canada March 7, 2024. Photo: Reuters