Two men were arrested following an exchange of gunfire outside the Criminal Court on Saturday night after they hurled a grenade into the parking lot, military spokesman Col Winthai Suwaree said on Sunday.
Col Winthai, the National Council for Peace and Order spokesman, said at a press conference that the two had been under surveillance after government security forces obtained information in joint intelligence operations by the military, police and administrative officials.
He identified the two as Yutthana Yenpinyo and Mahahin Khunthong, who on Saturday night drove a motorcycle to the Criminal Court on Ratchadapisek Road and hurled an RGD5 grenade into the court's parking area.
The military officials, who followed the two in a car, hit their motorcycle with the car, causing it to fall to the ground. The two men resisted arrest, leading to a minor exchange of gunfire. Mr Yutthana was hit four times and wounded. He was admitted to a hospital. Mr Mahahin was taken into military custody for interrogation, Col Winthai said.
The NCPO spokesman said the attack was intended to create unrest and fear.
The case is now being jointly handled by the military peace-keeping force and the Royal Thai Police Office.
Prime Minister Prayut Chan-o-cha is being kept updated on the incident. He ordered authorities to conclude the case as soon as possible and keep the people informed of all developments, Col Winthai said.