Six people were found dead at an upmarket hotel in Bangkok on Tuesday, including at least one American national of Vietnamese descent, the Thai government said.

Police said in a separate statement that the six people were all foreign nationals. The prime minister has ordered a swift investigation to stem any damage to the tourism sector.

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 South East Asia’s second-largest economy.

“The prime minister has ordered all agencies to urgently take action to avoid impact on tourism,” the 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.

The US and Vietnamese embassies in Bangkok did not respond to calls from Reuters.

Police officers found the bodies at the Grand Hyatt Erawan after receiving a call from the hotel’s staff at about 5.30pm reporting that there had been deaths, the Thai police said in its statement.

Police and medical services could not immediately be reached for further comment.

The Grand Hyatt Erawan, which has more than 350 rooms and is located in a popular tourist district known for luxury shopping and restaurants, did not immediately respond to calls or an email seeking comment.