Investigators said one suspect from Ontario, 58-year-old Michael Peterson, had more than 500,000 images and 7,500 videos of suspected child pornography on his computers.
He was charged in a three-count criminal complaint with possessing, receiving and distributing child pornography.
Authorities said another suspect, 37-year-old David Jelaca of La Quinta, admitted in emails that he has had sexual contact with girls as young as 15.
Immigration and customs officers worked with Homeland Security investigators to make the arrests.
The Associated Press contributed to this report.