AlphaBay users are fearing the worst after the world’s largest darknet marketplace went offline on Tuesday night and associated Bitcoin accounts were subject to huge withdrawals of funds.

The site – which provides a platform for users to buy and sell drugs, guns and other assorted illegal items – is said to have gone down at around midnight, locking users out of their accounts.

That has prompted fevered speculation on various forums that its owners have committed a classic “exit scam”; basically, running off with the funds of both buyers and sellers which are normally held in escrow by site admins.

That’s what happened with Silk Road successor Evolution back in 2015, with the site administrators netting an estimated $12m.

Adding to the rumors of something similar afoot at AlphaBay are blockchain records showing withdrawals of over 1,400 Bitcoins ($3.8m) from accounts linked to the marketplace.

However, a Reddit user who appeared to know something of the situation sought to quell the rising panic, claiming the servers – located in a variety of locations – were simply taken down for “annual maintenance”.

“Transfer of btc is necessary for users security. Let's say you own a chain banks, and one location needs updating done to it's vaults. During the down time that you have your location's vaults being updated would you keep your customers money exposed to internal threats, and out side threats?” they continued.

“No, you would relocate the valuable resources inside to another secure location. Also it stops exposing the sites real storage blocks from outside threats.”

If this user is telling the truth, then the site should be back up and running at some point today.

The Reddit user, ‘BigBoyRoy1’ also warned AlphaBay buyers and sellers to be on alert for follow-on phishing and market scams looking to capitalize on user panic and their desire to regain access to funds and accounts.

AlphaBay is said to be three times bigger than its nearest competitor, with over 225,000 listings.