
The shooting after the protest at SCB Park ended on Wednesday night involved students from rival schools who worked as guards during the rally, according to police.
Pol Maj Gen Piya Tawichai, deputy commissioner of the Metropolitan Police Bureau, said on Thursday the incident occurred after the rally ended outside the headquarters of Siam Commercial Bank (SCB).
Gunshots were heard and an explosion, possibly a firecracker, about 10pm.
The deputy commissioner said a young man with one group of vocational students fired shots at a group of rival students. One person was wounded, taken to Praram 9 Hospital and admitted to intensive care.
The students were from Minburi Technical College in Bangkok and Pathumthani Vocational Education College in Pathum Thani province.
Pol Maj Gen Piya warned organisers to ensure their rally guards were unarmed.
Police later reported that two people had actually been injured during the shooting on Wednesday night.
The second was the gunman, who was beaten up and later taken to Saint Louis Hospital.