There are rumors that some of the six bodies discovered dead at a five-star hotel in Bangkok were caused by poisoning.
Citing local police, the Matichon newspaper and other Thai media first reported a gunshot in the nation's capital on Tuesday night.

Matichon, however, subsequently stated that poisoning had been determined to be the cause of death.

The five-star Grand Hyatt Erawan was reportedly the scene of the attack. Images of cops entering the hotel lobby have surfaced.

According to Thailand's Foreign Ministry, there had been no indications of a struggle or violence, and the deceased were reportedly two Vietnamese Americans and four Vietnamese nationals.

It said three of the dead were men and three were women.

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, without elaborating further.

Another unnamed police source from the local Lumpini police station told media that the victims were found foaming at the mouth. Officials also said the apparent poisonings did not appear to be an act of self-harm.

Police officers found the bodies of six deceased foreign nationals at the Grand Hyatt Erawan after receiving a call from the hotel's staff at around 5.30 pm reporting that there had been deaths, the Thai police said in its statement.

Thailand’s prime minister Settha Thavisin has ordered a swift investigation into the incident to stem any damage to the tourism sector.

Thai media reported that the prime minister visited the scene and appeared “stressed” as he refused to give any interviews to journalists at the scene.

Reports have also emerged that the Russian energy minister was due to hold a meeting at the hotel on Wednesday.

Medical services could not immediately be reached for comment.

Matichon initially said reports had emerged of a shooting at a “famous hotel” in the Ratchaprasong district of the city at 7.30pm local time (1.30BST).

It said five people died inside a room and one person outside.

The Grand Hyatt Erawan is described on its website as a five star hotel in the capital’s key commercial and diplomatic district, next to Erawan Shrine. It has 380 rooms and 44 suites and its luxury facilities include a spa and restaurant.

Ratchaprasong is a shopping and entertainment district next to the well-known Siam area, which is dominated by large shopping malls such as MBK Center.

Last year a teenager was arrested after he shot dead two foreigners at Bangkok’s Siam Paragon mall.