AlphaBay Market, one of the dark web’s largest markets for drugs, guns, and other illegal paraphernalia, has been shut down since midnight Tuesday night. Although the site is sometimes down for maintenance, the site’s admins have yet to comment on the downtime, leading some to speculate that the market may have disappeared for good.

There’s evidence of massive bitcoin withdrawals from the site’s accounts, with one blockchain record showing withdrawal transactions totaling 1,479.03904709 BTC (roughly $3.8 million), from an array of smaller accounts. That’s led to suspicion from some users on Reddit and Twitter that the site’s admins may have shut down the site in order to steal user funds.

So-called exit schemes are common among dark web marketplaces, with admins abruptly pulling sites offline, stealing the bitcoin stored in user accounts, and never resurfacing. In May, the Outlaw market shut its doors, claiming that it was hacked, although the timing of the alleged hack coincided with surging bitcoin prices. In 2015, the Evolution marketplace disappeared with $12 million of user money in a similar scheme.