Ho Chi Minh City-based company Modern Tech has gone dark after allegedly deceiving 32,000 people into investing an estimated VND15 trillion (US$660 million) into two fake cryptocurrency projects.

Dozens of disgruntled investors gathered in front of Modern Tech’s headquarters in the business district of Ho Chi Minh City on Sunday, carrying signs denouncing the company’s fraudulent activities and requesting to be refunded, reports local news outlet Tuoi Tre.

The owner of the Vietnamreal building where Modern Tech was initially headquartered told reporters on Monday that the company had cleared out its office about a month prior to the events.

Modern Tech had claimed to be the authorized Vietnamese representative of two cryptocurrencies, Ifan and Pincoin. It was responsible for conducting two initial coin offerings (ICOs) on their behalf.

Ifan was marketed as “the most advanced social network” for celebrities and artists, enabling them to better connect with their fans. Its native token was intended to be used for downloads, album and live performances ticket purchases, as well as merchandises and endorsements.

Pincoin was marketed simply as an “investment opportunity” promising up to 40% in monthly profit. It claimed to be overseen by the so-called PIN Foundation.

Investors were told that the tokens they received would see their value skyrocket once they hit the secondary market. Modern Tech also promised an 8% commission for every new member introduced.

Investors grew suspicious when the company began to stop paying commissions in real money, but in tokens. Investors could see the value of their investment rise on a daily basis in the dashboard but would never be able to withdraw them in cash.

They took on social media and forums to lament, some claiming they had lost a fortune investing in the alleged Ponzi schemes.

Scams in the cryptocurrency space have become rampant as thieves look to tap into the bitcoin frenzy to lure naive investors into putting their life savings into “the next big thing,” often promising absurdly high rates of return.

In March, cryptocurrency startup Giza Device vanished after raising US$2 million in cryptocurrencies in a fake ICO. The funds were supposed to be used to fund the development of a “super secure storage device” for cryptocurrencies.

Earlier this month in India, self-proclaimed “cryptocurrency guru,” businessman and Bitcoin entrepreneur Amit Bhardwaj was arrested for allegedly scamming investors out of Rs 2,000 crore (US$307 million) in the state of Indian state of Maharashtra alone.

Bhardwaj, who was on the run for almost a year, was arrested at the Bangkok airport on April 4, and later brought to Pune to face the trial. He is accused of cheating investors with Bitcoin-based Ponzi schemes. Highly-placed officials involved in investigations told India Today that Bhardwaj’s alleged scam could run between Rs 5,000 crore (US$769 million) and Rs 13,000 crore (US$2 billion).

Bhardwaj operated several ventures including GainBitcoin, GBMiners, MCAP and GB21. His book Cryptocurrency for Beginners was promoted on social media by numerous Bollywood actors.