TORONTO (AP) — More than 100 men have been arrested for allegedly looking to buy sex from underage girls, an Ontario police force said Friday.

York Regional Det. Sgt. Thai Truong said undercover officers put ads online to find men looking for sex. When men responded to the ads, they were told that they were talking to children, aged 13 to 16. Truong said that most of the men stopped communicating at that point aside from the 104 men who were arrested in the sting. The officers involved were undercover agents.

Truong said there were no actual child victims in the police investigation that took place over four years.

"All of the men that were arrested were arrested for essentially attempting to purchase prostituted children. So if we look at it from another perspective, from a preventative measure, we've stopped 104 men from purchasing 104 children," he said during a press conference at York Regional Police headquarters in Aurora, Ont.

A total of 64 cases are before the courts, while 40 cases have been resolved. A total of 32 accused men pleaded guilty, five cases were withdrawn, three went to trial and were found guilty.

"The majority of underage trafficked children are being trolled via social media. The Internet is different today than it was years ago. Growing up today is a lot different than it was 10 years ago," said Truong. "The biggest challenge for us when we're dealing with prostituted children is that enlisting their co-operation is very, very difficult. Getting them to trust me, getting them to tell us what has happened is challenging," he said.

Truong said child sex trafficking is a growing problem in Canada and that the average age of entry into the human trafficking sex trade is about 15 years old.