PATTAYA — Two Chinese nationals were arrested after a car crash in Chonburi led police to uncover a cache of military-grade weapons, explosives and C4 explosive devices at a rented house in Pattaya area, police said on Friday.
The incident began on the evening of 8 May when a white sedan overturned on its own along the old railway parallel road in Huay Yai subdistrict, Bang Lamung district, Chonburi province. Police believed rain and slippery road conditions may have caused the accident.
Officers from Huay Yai Police Station arrived at the scene and found two Chinese nationals identified as Ma Yu Hsih and Sun Mingchen. During an inspection of the vehicle, police discovered a handgun inside the car and detained both suspects for questioning.
The investigation later expanded to a house in The Maple village in Moo 2 of Huay Yai subdistrict, where authorities discovered a large cache of weapons and military equipment.
Items seized included two M4 rifles, 13 fully loaded magazines, two detonators, hand grenades, ammunition and multiple bulletproof vests.
Police sources said two black and brown tactical vests were found packed with C4 explosives. All items were seized for further examination.
Authorities said the suspects were Chinese men from China’s plateau region who entered Thailand using alien identification documents. Police said they had no clear occupation and rented the house in Pattaya area.
During questioning, the suspects allegedly claimed they purchased the weapons through social media and arranged delivery in Rayong province. They reportedly told investigators the weapons were bought for personal collection purposes and for use in a planned suicide attempt.
Police said Sun Mingchen, 31, told investigators he previously operated a liquor business in Cambodia before relocating to Thailand following border tensions. He allegedly claimed he intended to carry out a suicide bombing because he suffered from depression.
Authorities said Sun entered Thailand on 27 January 2026 through Suvarnabhumi immigration checkpoint, while the female Chinese national entered on 24 April 2026.
However, investigators said they were unconvinced by the explanations because the seized weapons were military-grade arms with high destructive capability typically used in combat operations.
Police said the explosives discovered included C4, a high-powered military explosive commonly associated with combat missions and terrorist attacks. Ammunition seized included 5.56mm M193 rounds.
National police chief Pol. Gen. Kitrat Phanphet ordered an intensive investigation into all security and public safety dimensions of the case. Police said no direct links to a planned attack had yet been established, but authorities were continuing to investigate the origins of the weapons and explosives.
Investigators also revealed further details about Sun’s background. Police said he had rented the house for 38,000 baht per month and had lived there for around two years.
Records showed he first entered Thailand in 2020 on a tourist visa and had frequently travelled in and out of the country since then.
Authorities also found that Sun allegedly possessed both Chinese and Cambodian passports, along with a Thai pink identification card issued to non-Thai nationals.
Police said his name also appeared on a house registration document in Sam Wa Tawan Tok subdistrict, Khlong Sam Wa district, Bangkok, and that he possessed a 13-digit Thai identification number.
Investigators found that his registered address had previously been transferred from a house in Chiang Dao district of Chiang Mai province on 14 November 2023. Authorities said they were still verifying the legality and circumstances surrounding the documents.
A resident in the housing estate, who declined to be named, told reporters the Chinese man appeared friendly and often greeted neighbours warmly.
The resident said villagers were shocked to learn explosives had been stored in the neighbourhood and feared widespread damage if the C4 devices had detonated.
