The death toll from a mass shooting in Thailand's capital Bangkok on Monday jumped to six as another critically injured security guard also died.

The suspected shooter opened fire at Or Tor Kor Market in Bangkok’s Chatuchak district, killing four people before turning the gun on himself, the daily Thai Enquirer reported.

The suspect was identified as a 61-year-old former security guard who had previously worked at the same company as the guards who were shot and killed.

After the shooting, the suspect sat on a bench in the middle of the market and fatally shot himself.

Authorities have launched an investigation to ascertain the suspect’s motive.