Six people were found dead at an upmarket hotel in Bangkok on Tuesday, including at least one American national of Vietnamese descent.
The Thai police said that the six people were all foreign nationals.
The incident, which took place at Bangkok's plush Grand Hyatt Erawan hotel, comes as Thailand looks to further promote its tourism sector, a key driver of Southeast Asia's second-largest economy.
"The prime minister has ordered all agencies to urgently take action to avoid impact on tourism," the Thai government said in its statement.
A police official, speaking on condition of anonymity, dismissed earlier reports in Thai media that the six people had been killed in a shooting.
"There is no sign of a shooting," the official told Reuters, adding that there were Vietnamese nationals among the dead. The official did not elaborate further.
Police officers found the bodies of six deceased foreign nationals at the hotel after receiving a call from the staff at around 5:30 pm reporting that there had been deaths, the Thai police said in its statement.
The Grand Hyatt Erawan, which has over 350 rooms, is located in a popular tourist district known for luxury shopping and restaurants.