A gunman opened fire at a market in Bangkok, killing at least five people before turning the gun on himself, according to Thai police.

An investigation is underway into the identity of the shooter and the motive for the shooting at Or Tor Kor market, which took place about 12:30 p.m. local time on Monday.

Four of the dead were security guards and the other victim was a woman who worked at the market, Bangkok Emergency Medical Center said. The gunman died by suicide, the center added.

No tourists were among the dead or injured at the market, which is popular with foreign visitors, in the Bang Sue district of the Thai capital.

Police said the gunman was Thai and had previously disputes with the market’s security guards.

This is a developing story and will be updated.