The shooter who killed dozens of people at two mosques in New Zealand last year was radicalized in part by right-wing anti-Muslim videos hosted on YouTube, a lengthy report on the attack found.

The report released Tuesday identified a failure by the country’s intelligence agencies to take seriously both the threat of white supremacist violence as well as warnings from Muslims living in the country about a rise in hate incidents.

It also found that the shooter, Brenton Tarrant, told investigators that while he frequented hangouts such as 8chan and 4chan, much of the anti-Muslim content he accessed was found on YouTube.

Jacinda Ardern, New Zealand’s prime minister, said that her government would implement all the recommendations raised in the report, according to The Associated Press. She added that she would be in contact with YouTube’s leadership over the issue.