Police are hunting for a man wearing a pink raincoat who may have fired shots at people protesting outside parliament during the violent confrontations on Tuesday.
Pol Maj Gen Piya Tawichai, deputy commissioner of the Metropolitan Police Bureau (MPB), said the man was believed to be a guard of the People's Movement protesters and is suspected of having opened fire at people converging on Thahan Road.
Six people suffered gunshot wounds during the confrontations on Tuesday, which involved police, anti-government protesters and pro-monarchy demonstrators. Police used tear gas and water cannon on demonstrators but denied using live rounds.
Some in the crowd were shot, according to medical workers, but it was unclear who opened fire. A photo of the man wearing the pink raincoat aiming what looked like a weapon at the protesters was shared on social media.
The spirit house at the Royal Thai Police headquarters is seen smeared with paint, after protesters gathered at the nearby Ratchaprasong intersection.
Pol Maj Gen Piya said police questioned witnesses and journalists covering the protests about the violence and their information was consistent with footage taken from security cameras in the area. Spent shells were retrieved from the scene and were being examined by police.
Pol Col Siriwat Deepor, a deputy police spokesman, said on Thursday police would press charges against pro-democracy protesters who vandalised police property during their rally near Ratchaprasong intersection on Wednesday evening.
He said that 13 surveillance cameras at the Royal Thai Police headquarters were spray-painted and the RTP nameplate, walls and lamps around the headquarters were defaced. Three border patrol police officers were slightly injured by objects thrown at them over the RTP fence and a police car's tyres were also flattened.
Meanwhile, Labour Minister Suchart Chomklin on Thursday denied any affiliations with a group of yellow-shirt demonstrators who were engaged in a brawl with pro-democracy protesters outside parliament.
A CCTV camera is seen covered in paint after the rally.
He insisted the yellow-shirt protesters, who were said to have travelled from Chon Buri which is Mr Suchart's political stronghold, were not his aides.
The minister said the people turned up out of their own free will to oppose the charter amendment bill put forward by civil group Internet Law Reform Dialogue (iLaw). The iLaw bill, however, was rejected on Wednesday by parliament.
"[The yellow-shirted protesters] came to the protest unarmed. But they were attacked, so they had to defend themselves," he said.
Ramet Rattanachaweng, spokesman of the Democrat Party, said he would file complaints against social media users who made baseless accusations against Parliament President Chuan Leekpai over violence outside parliament.