Thai police raided a hotel in Pattaya after a tip off about an illegal orgy, leading them to a group of 18 expats from around the world having sex with young Thai women.

On Saturday night, Thai police in Pattaya, known as the sex capital of the world, received a tip that guests of the Tulip Hotel were paying 1,500 Thai Baht, roughly $48, to participate in orgies organized on the weekends.

Police raided the 30-room hotel, bursting into a floor dedicated as a “play zone” to catch 18 expats from the U.K., the U.S., Australia, Germany, Canada, Russia, Malaysia and China. The men, who were reportedly caught naked and sweaty, scrambled to cover themselves with towels and hide the faces of their sex partners, according to Daily Mail.

The men were reportedly questioned and then released.

The owner of the hotel, 53-year-old Chinese-national Sheng Liao Yang, was arrested for hosting sex parties and suspicion of running a hotel without a license.

District Sheriff Naris Niwapantawong revealed that the international orgy ensemble traded sex partners and that they were caught while having sex.

“To attend the event, participants had to register through a website. There was a rule that party members must be male and female couples. The cost per night was 1,500 baht per person,” Niwapantawong said.

Condoms, sex toys, and lubricant were found and collected as evidence.

Prosecutors will now build a case against the hotel owner.