The head of OpenAI has written a letter apologizing that his company didn’t alert law enforcement about the online behavior of a person who shot and killed eight people in Tumbler Ridge, British Columbia.

In the letter posted Friday, Sam Altman expressed his deepest condolences to the entire community.

“I am deeply sorry that we did not alert law enforcement to the account that was banned in June,” Altman said. “While I know words can never be enough, I believe an apology is necessary to recognize the harm and irreversible loss your community has suffered.”

The letter, dated Thursday, appeared on British Columbia premier David Eby’s social media and also on the local news website Tumbler RidgeLines on Friday.

On 10 February, police say an 18-year-old alleged shooter, identified as Jesse Van Rootselaar, killed her 39-year-old mother, Jennifer Jacobs, and 11-year-old stepbrother, Emmett Jacobs, in their northern British Columbia home before heading to the nearby Tumbler Ridge Secondary School and opening fire, killing five children and an educator before killing herself.

Twenty-five people were also injured in the attack.

After the incident, OpenAI came forward to say that last June the company identified Van Rootselaar’s account using abuse detection efforts for “furtherance of violent activities”.

The San Francisco technology company said it considered whether to refer the account to the Royal Canadian Mounted Police but determined at the time that the account activity didn’t meet a threshold for referral to law enforcement. OpenAI banned the account in June for violating its usage policy.

At the time, Eby said it “looks like” OpenAI had the opportunity to prevent the mass shooting.

In his letter, Altman said he had spoken with Tumbler Ridge mayor Darryl Krakowka and Eby and they “conveyed the anger, sadness and concern” felt in the community. It was agreed a public apology was warranted but time was needed for the community to grieve.

“I want to express my deepest condolences to the entire community,” Altman said. “No one should ever have to endure a tragedy like this. I cannot imagine anything worse in this world than losing a child.

“My heart remains with the victims.”

Altman reaffirmed his commitment to find ways to prevent similar tragedies.

“Going forward, our focus will continue to be on working with all levels of government to help ensure something like this never happens again,” he said.

Eby, in a social media post, called the apology “necessary, and yet grossly insufficient for the devastation done to the families of Tumbler Ridge.”