A Toronto-based child pornography investigation has led to the rescue of nearly 400 children and the arrest of 348 adults around the world. Canadian police are calling it one of the largest child porn busts they’ve ever seen.

Over 100 people in Canada and 76 people in the U.S. have been arrested, according to the Associated Press. Australian police say that 65 men have been arrested there, and six children had been rescued from exploitation.

“It is alleged that officers seized hundreds of thousands of videos detailing horrific sexual acts against very young children, some of the worst that they have ever viewed,” said Toronto police Inspector Joanna Beaven-Desjardins.

The investigation began with a Toronto man who allegedly instructed people around the world to film videos of children performing sexual acts, which he would distribute through a company he had been running since 2005.

Brian Way, 42, has been charged with 24 offenses and is currently in jail. He was also charged with leading a criminal organization, which Canadian investigators say is a first for child porn.

The investigation, according to the Associated Press, began in 2010.

[AP]