A full-blown dark web drug crackdown is in the works, and it's not stopping with the Silk Road.

On Thursday the FBI along with other law enforcement agencies including the Department of Homeland Security and Europol announced that it had seized the Silk Road 2, perhaps the most well-known drug market to appear on the Dark Web since the takedown of the original Silk Road last year. What it didn't announce is that at least two other drug market sites have also been busted, and more takedowns are likely coming. The drug markets Hydra and Cloud 9 now both display the same "This Hidden Site Has Been Seized" notices as the Silk Road 2, emblazoned with the logos of the FBI and Europol. Several other popular dark net markets were down Thursday morning, as well, though they didn't display that banner. An FBI spokesperson tells WIRED that there will be more than three market seizures in total, with the full extent of the operation set to be revealed by Friday.

The string of drug market busts appears to be part of Operation "Onymous," a global law enforcement effort that has already led to the arrest of three people. Yesterday the FBI arrested Blake Benthall in San Francisco and accused him in a criminal complaint of running the Silk Road 2 drug site under the pseudonym "Defcon." Two other suspects were arrested separately in Dublin, and cops say they've seized from them $250,000 worth of drugs and as much as $2.5 million worth of bitcoin. An FBI spokesperson confirms that the arrests are part of a "coordinated law enforcement action," but not part of the same case.

The Silk Road 2, which launched a year to the day before its takedown, took on the branding of the original Silk Road drug market to attract hundreds of thousands of users. According to the criminal complaint against Benthall, it was making $8 million a month in bitcoin-based sales before the takedown. Cloud 9 and Hydra, by contrast, were smaller sites but with loyal followings. In a count by the Digital Citizens Alliance in August, Cloud 9 offered 1,600 drug listings, and Hydra listed 1,151.

Both smaller sites attracted users by implementing a bitcoin feature known as multi-signature transactions. When coins were spent on the site, they were put into an account controlled jointly by the buyer, seller, and site administrators, and two out of three of them had to sign off on that transaction to move the funds. That feature was designed in part to prevent law enforcement from easily seizing the sites' bitcoins, and may in fact limit the losses suffered by their users following these takedowns.

As of Thursday afternoon, the two largest drug markets—Agora and Evolution—were both still online.

Just last week, New York Senator Chuck Schumer called for a renewed crackdown on all dark web drug trade in an open letter to Attorney General Eric Holder. That trade, after all, has more than doubled in size by some measures since the takedown of the original Silk Road a year ago.

On the Reddit forum devoted to dark net markets, users expressed a mixture of dismay, panic, and gallows humor.

"Please no, Agora is like my Walmart for drugs [but Cloud 9] was the ma and pa store that I grew to love," wrote one user named hellokittycustomer.

"NEW GAME," wrote another called xanaxxanaxxanax. "One hit of any drug of your choice every time another market goes down."

"I predict that we will bounce back, stronger than before," added another user named Infinite. "But at this point I'm pretty freaked out."