A 25-year-old man tied up by armed robbers managed to free himself of his bonds and then shot dead one of four gunmen who held up his uncle's food shop in Bang Pahun district of Ayutthaya province, a report said on Thursday.
The shop owner's nephew, Sriwichai Presiri, told police that four armed and hooded men burst into his uncle's shop, which is part of the family's home, after arriving on two motorbikes.
The men entered the store, which sells larp (Lao minced meat salad), claiming they were policemen. The robbers used wire to tie up his aunt, uncle, and himself, he said.
The attackers then repeatedly assaulted them before ransacking the house and stealing 20,000 baht in cash and a gold necklace weighing one baht, he said.
Mr Sriwichai said he managed to free himself from his restraints and get hold of his pistol. He then fired at the assailants, hitting one of them in the head and killing him.
The three other robbers fled on their motorcycles.
Police said the dead man was identified as Montri Roongjamras, 53, who had previously been convicted of robbery and was recently released after completing a prison term.
Police were interviewing witnesses and said they would track down the three other robbers.