Officers rushed to the Grand Hotel Resort last night after reading a ''Help Me'' message on a smartphone application called Line.
In Room 401 they found two Russians holding two other Russians prisoner. The prisoners had been beaten.
One of the victims told the police that he had been kidnapped at gunpoint last night and taken to the hotel room, where the gang members threatened him.
He was beaten after refusing to hand over 1.2 million baht, or the deeds to a new bar that is due to open on Samui's Chaweng Beach soon.
The man later told police it was not the first time the Russian gang had extorted him, Samui Police Superintendent Colonel Jamnoch Keawkhaw told Phuketwan today.
''The man told us he had handed over 1.6 million baht on previous occasions,'' the colonel said. ''That's why he came to the police and organised to send us a message if he got into difficulties.
''Now we have the evidence that we needed,'' the colonel said. A third Russian man was arrested today.
The Russian gang had organised ropes in the room so that they could escape over the balcony if necessary, But they weren't quick enough last night.
News of the kidnapping and extortion is likely to cause alarm on Phuket, where concern about Russian ''mafia'' moving from Samui and Pattaya is already high.