Seven top officials of the website Backpage.com, long accused of facilitating child sex trafficking, have been arrested after a grand jury in Phoenix, Arizona, issued a 93-count indictment alleging conspiracy and money laundering, and the government on Friday seized all of Backpage’s websites around the world.

The indictment was unsealed Monday after all defendants made their first appearances before a magistrate there. Among those charged are the site’s founders, Michael Lacey and James Larkin.

The indictment accuses Backpage of facilitating prostitution committed by those posting ads on the site, specifically citing 17 victims trafficked on Backpage, some as young as 14. Authorities also allege the company laundered some of the estimated $500 million in prostitution-related revenue the site has reaped since its launch in 2004.

“Virtually every dollar flowing into Backpage’s coffers represents the proceeds of illegal activity,” according to the indictment.

An official with the Justice Department said in a background briefing that the hosting of trafficking ads on Backpage was not inadvertent, but instead the result of “consistent and concerted action” taken over the years. “This is not a website that let the occasional ad slip thru the cracks of their review system,” an official said Friday, as the government was taking down Backpage’s websites.

A Senate report issued last year said that Backpage had gross revenue of $135 million in 2014 and expected those numbers to rise. The report said Backpage ran sites for 943 locations in 97 countries and 17 languages.

Backpage has argued that it assists law enforcement in tracking down victims and perpetrators of crimes, which some police officials have corroborated, and is not a participant in the advertising on the site. Some in the sex worker industry say that removing Backpage from the internet takes away a safe mechanism for screening clients, and that the ads will simply move to sites outside the country, or to social media.

The federal investigation in Phoenix was first disclosed by Backpage in a court filing in February 2017. Phoenix is where Backpage was created, by Lacey and Larkin as owners of the New Times alternative weekly newspaper chain, and federal officials said that is where the company’s American bank accounts are located, although they alleged that money was funneled through banks in Iceland, Hungary, Liechtenstein and the Netherlands.

Backpage’s general counsel, Liz McDougall, did not return messages seeking comment.

Backpage is a classified ads website which grew in prominence, and income, after Craigslist.com stopped hosting “Adult Services” ads in 2010. Embedded among the ads for adult prostitutes on Backpage are solicitations for teenaged girls and boys, anti-sex trafficking advocates said, enabling pimps to repeatedly sell children for sex. Though Backpage closed its “Adult Services” section in January 2017, the ads promptly reappeared in the “Dating” section, most recently with very little written copy accompanying photos of the males and females seeking dates.

One 16-year-old girl in Chicago was slain in 2016 after responding to an ad placed by her pimp on Backpage. The indictment discusses another girl who was murdered after being prostituted on Backpage, a case in which the killer then attempted to burn his victim’s body. The National Center for Missing and Exploited Children has said that 73 percent of the child trafficking reports it receives from the public stem from Backpage.

“For years, Backpage.com has been a major hub of sex trafficking, the place where some of our nation’s most vulnerable women and children have been bought and sold,” said Lauren Hersh, national director of World Without Exploitation. “The closure of Backpage removes one of the most prolific online platforms of exploitation. It is high time to hold websites accountable for the harm they knowingly cause by facilitating sexual exploitation.”

Mary Mazzio, whose documentary “I Am Jane Doe” featured numerous women trafficked on Backpage said, “I don’t think any of the children who filed suit against Backpage ever thought their fight for justice would result in a federal indictment or a legislative response. That Congress and the Department of Justice would respond with urgency to the voices of these children, as well as survivors from across the country, who lined up, shoulder to shoulder in support of these children, is stunning.”

Seizing websites is not a new tack for the Justice Department. The department last year said it had shut down AlphaBay, a site on the dark Web that functioned as an illicit marketplace for guns, drugs and fake documents. It has previously seized websites suspected of facilitating prostitution, such as RentBoy.com and MyRedBook.com, and obtained convictions of the sites’ operators.

But Backpage had evaded prosecution, in large part by invoking the Communications Decency Act. Enacted in 1996, the law provides legal immunity for website operators for content posted by third parties, so long as the operators weren’t involved in creating the content. Lawsuits brought by women who had been trafficked on Backpage were dismissed by federal courts in Chicago and Boston because of the immunity granted by Section 230 of the decency act, as was a criminal case in California filed by the attorney general there.

The courts in each case invited Congress to amend the decency act. So the Senate subcommittee on investigations launched a probe into Backpage, and found that Backpage employees were editing prostitution ads to delete references to underage girls, while still allowing the ads to be posted.

In addition, The Washington Post found that Backpage had hired a contractor in the Philippines to solicit ads from prostitutes advertising on other websites, creating ready-made ads for them on Backpage, though Backpage had said it was not involved in creating content.

Members of the House and Senate both launched bills to amend Section 230, and a combined version of those passed both houses last month. Nicknamed “FOSTA,” for the Fight Online Sex Trafficking Act, it would enable victims and state prosecutors to pursue websites in criminal and civil court without being blocked by Section 230. It is awaiting President Donald Trump’s signature or veto.

But opponents of the bill noted that federal prosecutors already had the tools to pursue websites such as Backpage, and indeed the new indictment did not require the new legislation. It accuses Backpage of “50 different instances in which the defendants are alleged to have knowingly facilitated a prostitution crime,” according to an official with the U.S. Attorney’s Office in Arizona. The official, along with another from the Justice Department, spoke on the condition of anonymity during a conference call with reporters Friday.

The indictments also discuss dozens of counts dealing with money laundering, which the officials said was an effort to keep the money from being traced. Since launching in 2004, Backpage has made “approximately $500 million dollars in prostitution-related revenue,” the Arizona official said. “The defendants took various steps to launder the money.” That included routing the money through seemingly unrelated businesses, wiring it through other countries and converting it in and out of “bitcoin and other forms of cryptocurrency,” the official said.

Officials said Friday their goal was to get the website taken down. “It is not unusual when a criminal organization has a domain name that is used as part of their criminal activity that we will seize it,” said the Justice Department official. The seizures began occurring Friday morning in Phoenix.