STORY: Thai police are investigating the deaths of six foreign nationals whose bodies were found in a room in a Hyatt hotel in Bangkok on Tuesday.
They are looking for a seventh person in connection with the incident.
All six were of Vietnamese descent, including two Americans.
Police believe they may have ingested something that killed them - and that they were not the victims of robbery or assault.
"Initially, from the scene inspection, there was no fight, no harm done. The property, as far as we can see, has not been ransacked. It is assumed that there was no intention towards the property and no outsiders entered, as determined from the fingerprint investigation. It is possible that it occurred from the inside, possibly a hideout, which indeed originated from the inside."
The U.S. State Department said Tuesday that it is monitoring the situation.
"Whenever a U.S. citizen dies in a foreign country, local authorities are responsible for determining the cause of death."
Thailand Prime Minister Srettha Thavisin - who visited the hotel on Tuesday - has ordered a swift investigation.
His office said he was concerned about the impact on tourism.
It's the key driver for the country's economy. Last year, 28 million visitors spent nearly $34 billion dollars in Thailand.
The tourism sector was shaken in October by a shooting spree at a luxury shopping mall close to the Hyatt in which two foreigners were killed.
