AlphaBay, a dark web marketplace that sells drugs and guns, has gone offline — sparking fear amongst its users that it is an "exit scam" stealing their funds.

However, a staff member has denied that the team behind the site has done a runner, writing on Reddit: "Will be back online soon. Servers under update."

Dark web marketplaces, accessible only via anonymising software Tor, let unscrupulous vendors sell almost anything — and are notorious for scams and fraud.

In March 2015, Evolution suddenly shut down in an apparent exit scam, stealing $12 million-worth of digital currency bitcoin that it was holding in escrow for vendors.

AlphaBay lets its users sell drugs, guns, counterfeits, stolen goods, and instructions for making bombs, among other items. (You can see what it looks like here.) But its sudden disappearance sparked concerns among its users that its admins too could be running off with their illicitly earned cash. Amid the chaos and panic, some threatened dark reprisals.

An old screenshot of a listing for marijuana on AlphaBay. AlphaBay/screenshot

"If it's an exit scam i'm gonna make a fundraising company to find and bomb them :)" said one Redditor.

"I'm not even in a position to loose any money and i would still donate to this if it meant, putting them in their f--king graves," wrote another.

A third assumed the worst: "they are sunning themselves with our f--king money."

Some, however, seemed to take pleasure in the chaos AlphaBay's downtime has been causing. "So lemme get this straight... You're surprised, and upset, that an illegal marketplace, which specialized in Fraud, and essentially stealing peoples money and identities, stole from you and you trusted them?" one user wrote. "Basically the reason such a place exists, and thrived for so long, is because of idiots like you... The f--kin irony man I love it."

The AlphaBay's staff member's Reddit post seems to have allayed many users' concerns, at least for now. The marketplace is very likely holding millions of dollars-worth of cryptocurrencies in escrow — meaning any exit scam could be highly lucrative.. "In my vendor profile is approx 50k USD right now in escrow ... 80 vendors like me is 4millions ... i'm sure there is more then 500 vendors with such amount =]" wrote one Reddit user.

We won't know for sure what's happening though until it comes back online — or doesn't. At the time of publication on Thursday, AlphaBay remained offline.