Police have confirmed that five people died during political protests since Saturday, all in the Ramkhamhaeng area.
The two latest casualties were off-duty soldier Pvt Thanasit Viengkham, 22, who was pronounced dead on Monday after he fell into a coma after a gunshot to the head around 2am on Sunday on Ramkhamhaeng Soi 24.
The other victim was found in a burnt-out bus in front of Ramkhamhaeng University on Sunday, said Pol Gen Jarumporn Suramanee, adviser to the Royal Thai Police Office, which is in charge of the investigation following clashes at Rajamangala Stadium between pro-government United Front for Democracy against Dictatorship supporters and students from Ramkhamhaeng University.
Pol Gen Jarumporn said Narumol Khampayak has filed a petition at Hua Mak police station claiming the charred bones found on the bus could be his son Suradet Khampaengjai, a 17-year-old student of Bangkapi Technology College, who disappeared on Sunday.
Ms Narumol believes that it is her son because of a ring, key and belt buckle found on the bus.
An autopsy and DNA test to determine whether the deceased is Mr Suradet is under way, Pol Gen Jarumporn said.
Suthi Fendi, 18, a friend of Mr Suradet, said that he was told that a Mr Benze and Mr Suradet drove a motorcycle from Ekamai Soi 30 to the stadium on Sunday afternoon where they were attacked with a pingpong bomb. The two rushed to hide on the bus, which was damaged and parked nearby. Mr Benze was quoted as saying that he heard someone shout "fire", so he fled the bus and lost Mr Suradet.
According to the Public Health Ministry, four people were killed _ the ministry has not included the body on the burnt-out bus in its toll _ and 263 others were injured in clashes during political protests around Bangkok between Saturday and yesterday.
Of the injured people, 129 were wounded on Monday alone. Of these, 87 were kept in hospital.
Pvt Thanasit is the third red shirt confirmed killed in the clashes in the Ramkhamhaeng area.
"He was a regular attendee at the red-shirt rallies three years ago," said Thasit Viengkham, Thanasit's uncle. "On Saturday night, when there was a call for volunteers to patrol the stadium and guard tens of thousands of us inside, many young folks such as vocational students and ordinary people like Mr Thanasit offered to do so.
"Then somebody came back and showed a blood-stained helmet and told the crowd inside the stadium that 'our friend' had been shot. I didn't know it was my nephew."
The violence intensified after 21-year-old Ramkhamhaeng University student Thaweesak Phokaew was shot dead by an unidentified gunman about 8pm on Saturday.
Two other red-shirt supporters _ Viroj Khemnak, 43, and Visanu Phaophu, 26, _ were shot dead on Sunday morning.
Wanchai Sornsiri, chairman of the Senate committee on human rights, said he has been assigned to find out who fired at demonstrators.
He demanded the government pay 7.5 million baht in compensation for each death and 250,000 baht for each funeral, to match what was offered to affected red-shirt demonstrators in 2010.