Five children were rescued and 35 adults were arrested during a crackdown on sex trafficking and prostitution during World Cannabis Week in Colorado.

FBI Public Affairs Specialist Deborah Sherman told Denver7 that authorities noticed a 35 percent increase in escort ads during last year's event.

"That said to us, 'there is a problem with this big event, just like many other big events, and we need to do this operation,'" Sherman said.

Sherman added that nearly 40 percent of escorts contacted during the sting told police they traveled to Colorado for the event.

“Whenever an event draws people from around the world, you will see an increase in sex trafficking,” said FBI Denver Special Agent in Charge Thomas Ravenelle.

Denver resident James Brent Anderson, 60, is one of those arrested in a sting that spanned from Fort Collins to Colorado Springs.

"Mr. Anderson allegedly went up to one of our undercover officers and attempted to buy a 7-year old for sex," Sherman said.

Anderson has been charged with Human Trafficking of a Minor, Soliciting Prostitution of a Child and Attempted Sex Assault of a Child.

Pedro Davalos was also arrested.

He's another alleged trafficker.

Officials said one of the recovered minors, a 15-year-old, was transported to Colorado from California by traffickers specifically for “420 Week.”

Of the adults arrested, nine were arrested for trafficking and 26 were arrested for prostitution, the FBI said.

The organizer of Denver's 420 Rally told Denver7 they will help police if they become aware of traffickers.

"We will not stand for and will assist with the prosecution of these human rights violators," said Miguel Lopez.

The FBI said more than a dozen other agencies were involved including the Adams County Sheriff’s Office, Arapahoe County Sheriff’s Office, Arvada Police Department, Aurora Police Department, Castle Rock Police Department, Colorado Department of Corrections, Colorado Springs Police Department, Colorado State Patrol, Colorado Trafficking and Organized Crime Coalition, Denver Police Department, Douglas County Sheriff’s Office, Golden Police Department, Homeland Security Investigations, Jefferson County District Attorney’s Office, Jefferson County Sheriff’s Office, Parker Police Department, Rocky Mountain Innocence Lost Task Force, Rocky Mountain Safe Streets Task Force, and Wheat Ridge Police Department.

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