Police in Laos have detained the manager and seven staff members of a backpacker hostel in Vang Vieng following the deaths of six tourists from suspected methanol poisoning, state media reported Tuesday.

Two Danish citizens, an American, a Briton and two Australians died following what media said was a night out in the town on November 12.

The victims include Briton Simone White, 28, two young Australians, Holly Bowles and her best friend Bianca Jones, and two young Danish women, Anne-Sofie Orkild Coyman and Freja Vennervald Sorensen, the BBC reported. Only one of the victims, 57-year-old U.S. citizen James Louis Hutson, was male. 

Police have detained the 34-year-old manager of the Nana Backpacker Hostel and seven other employees for interrogation, the Laos Post said on Tuesday.

Local media reported that all those detained were Vietnamese nationals.

The owners of the hostel, which is now closed, have previously denied serving illicit alcohol, the BBC reported.

Vang Vieng has been a fixture on the Southeast Asia backpacker trail since Laos’ secretive communist rulers opened the country to tourism decades ago.

The town was once synonymous with alcohol and drug-fuelled jungle parties for backpackers but has since re-branded as an eco-tourism destination.

Alcohol tainted with methanol is suspected to be the cause of the deaths.

Methanol is a toxic alcohol that can be added to liquor to increase its potency but can cause blindness, liver damage and death.

On their travel advice websites, U.K. and Australian authorities have warned their citizens to beware of methanol poisoning while consuming alcohol in Laos.

On Saturday the Laos government expressed “sincere sympathy and deepest condolences to the families of the deceased,” adding an investigation was underway to find the cause of the incident.