Local police identified the shooter as Chaturong Suksuk, a former soldier and paralympic athlete.
One person was also injured in the shooting that took place at about 11.25pm local time.
Suksuk, and his bride, 44-year-old Kanchana Pachunthuek, lived together for three years before they decided to get married. The couple had their wedding ceremony on Saturday morning, according to Bangkok Post.
Guests noticed the groom did not look happy, reports said. Suksuk, 29, left the wedding party suddenly amid the celebrations at a house in Wang Nam Khieo district in north-east Thailand, went to his car and returned with a pistol.
The groom then started firing shots that killed the bride, her 62-year-old mother and 38-year-old sister, and one other guest. One guest was reported to have sustained serious injuries.
Suksuk then shot himself and died on the spot, according to the police.
A police spokesperson was quoted as saying by the BBC that the groom “was quite intoxicated at the time”.
The motive, however, remained unclear. Police said 11 bullets were recovered from the scene of the shooting. He reportedly bought the gun and the ammunition legally last year.
The groom was a former marine soldier in Thailand and one of his legs was amputated after an accident.
He was also a member of the Thai paralympic athlete team that participated in the 11th Asean Para Games held in Indonesia last year and won a silver medal in swimming.
This incident comes just days after Thai interior minister Anutin Charnvirakul signed an order to suspend the issuance of gun licences for a year.
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