Former Democrat MP Thaworn Senneam, one of the PDRC leaders, brought protest security guard Banjong Pengsakul to Rajavithi Hospital after his left wrist was hit by a bullet while he was on security duty near
the Finance Ministry, one of the three protest sites.
Mr Thaworn said at around 10pm, a homemade 'ping-pong' bomb was hurled into a group of guards which put them on higher alert.
At 11pm, two gunmen on a motorcycle fired six shots into the group of guards, one of which struck Mr Banjong.
Mr Thaworn said he believed the political conflict was the reason for the attack.
At Khok Wua intersection, near the Democracy Monument on Rajdamnoen Avenue, one of three protest sites, a volunteer PDRC guard was wounded in at attack using homemade ping-pong bombs.
A guard witnessing the incident said the guards clashed with a group of teenagers on motorcycles and sounds of explosions were heard.
A guard identified as Sornchai Tuksuwan was seriously injured on his left arm and was sent to Bangkok Metropolitan Administration (BMA) General Hospital while a teenager was also wounded and sent to Vajira
Chana Songkram police inspected the crime scene bringing along a teenage suspect who was detained by the anti-government guards for questioning.