Eight staff members of a backpacker hostel in Laos have been detained by local authorities as they investigate the deaths of six foreign tourists from suspected methanol poisoning, according to state-affiliated media in the Southeast Asian country.

The deaths of two Australian teenagers, a British woman, an American man and two Danish women – and reports of others taken ill – prompted warnings last week from several Western nations about the potentially fatal consequences of drinking tainted alcohol in Laos.

The employees of the Nana Backpacker Hostel in the northern town of Vang Vieng, all Vietnamese nationals aged between 23 and 44, were arrested Monday by local police, state-affiliated newspaper the Laotian Times reported.

Part of the investigation has focused on reports the tourists were offered free shots of alcohol at the hostel, where at least five of those who died had stayed.

The hostel manager and owner, who are also Vietnamese, were previously detained for questioning by police, according to the Associated Press. The manager had earlier said the two Australian women joined more than 100 guests for free shots at the hostel before leaving for a night out, but he denied that other guests had reported any issue, AP reported.

The victims’ respective governments have confirmed their nationalities and deaths, but many details of the suspected mass poisoning remain unclear, frustrating families and fellow travelers trying to piece together what happened in Vang Vieng.

A statement from the official Lao News Agency (KPL) Friday reported that “the consumption of tainted alcoholic beverages” was the suspected cause of the deaths. But Laos authorities have not given any indication of where and how tainted alcohol might have got into the supply chain.

Travelers conduct own investigation

Meanwhile, the victims’ families are grappling with the abrupt loss of their loved ones.

The bodies of 19-year-old best friends Holly Bowles and Bianca Jones were returned to Australia on Tuesday night. Speaking to reporters at Melbourne airport, their fathers thanked supporters and praised efforts from the Australian government, according to Nine News.

But Mark Jones said the families were still no closer to getting answers about how their daughters had died, Nine News reported.

“We want to grieve. We miss our daughters desperately,” Jones said, after news broke of the arrests in Vang Vieng. “I was happy to hear that there’s been some movement over in Laos … I would continue to urge the Laos government to continue to pursue whomever.”

Methanol is an alcohol chemical commonly used in industrial solvents, cleaning products and fuel, though it can be added to alcoholic drinks either inadvertently through traditional brewing methods or deliberately – usually in the pursuit of profit.

In recent decades, Vang Vieng had earned a notorious reputation as a hedonistic party center where travelers could easily access cheap alcohol and illicit drugs.

But in 2012, the government ordered a crackdown following a string of fatal accidents linked to poor safety standards and a culture of excess along the river that flows through the town, reinventing Vang Vieng as more of an eco-paradise and adventure travel hub.