Florida has charged 178 people with human trafficking and the production and possession of child pornography.

The arrests ended a two-year human trafficking investigation called Operation Stolen Innocence conducted by Tallahassee police. The charges include solicitation, lewd battery and human trafficking of minors.

The investigation uncovered "a massive amount of electronic evidence that required months to examine," Fox News quoted the Tallahassee police as saying in a news release. The electronic evidence, authorities said, helped investigators to process the case and find out how many suspects were involved.

The investigation started in November 2018 after detectives saw photos of a 13-year-old girl on a website that advertises sex for money. The police's special victims' unit set up an operation to rescue a young girl, authorities said.

However, the rescue revealed a more complex underground business involving a large child sex trafficking network.

According to Elizabeth Bascom, one of the principal investigators, the child exploitation was "horrific" and that abuse may have started before her 13th birthday. Police chief Lawrence Revell said the child was recovering. She is expected to give evidence. It isn't clear how many cases will go to trial.

Authorities said all suspects are from the U.S. southeast region, spanning Alabama and Mississippi. Child sex trafficking has been on the rise in the U.S. in the past few years.

The National Human Trafficking hotline said there had been almost 900 cases of human trafficking in Florida this year.

Some 50,000 people are trafficked in the U.S. each year and the industry is said to generate around $150 billion worldwide, prosecutor and state attorney's office felony director Lorena Vollrath-Bueno said.