A man fatally shot six members of his family including his wife and two young children before killing himself at a New Year party in his home in Chumporn, Thailand.

Thailand police said Tuesday that a heavily drunk Sucheep Sornsung, 41, returned home shortly after midnight to celebrate with his wife and in-laws. He then quarreled with his family before he shot them all, including his six-year-old daughter and nine-year-old son. He then turned the gun on himself.

The other people killed in the incident include two men and two women aged between 40 and 71. A seventh person, his brother-in-law, was also injured in the shooting.

Tinnakorn Onmuk, the brother-in-law, said, “During the countdown, we were having fun in front of the house, and … he came into the house drunk.” 

He then shouted “I’m already here. You are not having fun yet, let me help,” before taking out the gun. "No one in this family appreciated me even though I helped out with everything. Let's get this over with then,” he yelled before opening fire at the family members.

Onmuk pretended to be dead after being shot in the stomach. Meanwhile, the suspect went into the bedroom and shot himself. His body was found with one gunshot to the head.

“All of the victims were his family members including his nine-year-old son and six-year-old daughter. They were shot either in the head or the torso… he was angry that as the son-in-law he was not being made welcome by his wife’s family,” said Police Lt Col Larp Kampapan, Chiangrai Times reported.

Major general Saharat Saksilapachai, commander of the provincial police, believes the shooting was triggered by a family dispute. He also feels alcohol had nothing to do with it.

"The (suspect) went to a party with his friends then came home to see his wife's family and they started arguing before he used his gun to shoot them. According to witnesses, the man did not drink a lot and we suspect that his rage came from old problems with his wife’s family,” he said, the New Straits Times reported.

Deputy provincial governor Somporn Patchimphetch said the suspect was released from jail in November after being convicted in an attempt to murder case.

In a similar incident in December, a Missouri man was charged for allegedly killing his girlfriend, his children and her mother. Richard Emery, who gunned down the family and also stabbed another woman while he was running from officers, now faces 15 charges including first-degree murder, armed criminal action and assault.