National police chief Pol Gen Chakthip Chaijinda told reporters on Friday a 500,000 baht reward was on offer for the capture of a gold-shop robber who killed three people, including a young boy, at a Lopburi department store on Thursday night.
The killer dressed in a balaclava, black shirt and camouflage trousers held up the Aurora gold shop inside the Robinson shopping mall at about 8.44pm on Thursday.
He approached the shop and fired at staff and customers, then he jumped over the counter and snatched gold necklaces worth around 500,000 baht.
As he left the mall he shot a security guard dead before fleeing on a red and white Yamaha Fino motorcycle without a licence plate.
Three people died of their wounds, including a woman and a two-year-old boy who was shot in the head while walking past the gold shop with his mother.
Police said the man used a 9mm pistol with a silencer attached.
A nationwide manhunt is underway to catch the killer with police ordered they can shoot to kill if necessary.