A sergeant-major said to be mentally ill shot dead two colleagues and wounded another soldier at the Army War College at the Army Training Command in Dusit district yesterday.
Special operations police were called to the college about 8.45am after initial reports said one person had been shot dead and another wounded.
A spokesman said the shooter was a mentally-ill soldier who was threatening to kill 10 people.
Army deputy spokeswoman Col Sirichan Ngathong later named the shooter as Sgt Maj Yongyut Mangkornkim, 59, an administrative clerk at the college and said that more than one person was killed.
Col Sirichan said Sgt Maj Yongyut walked into the administration office about about 8.45am carrying a gun and opened fire, killing two colleagues identified as Sgt Maj Nopparat Intarasunthorn and Sgt Maj Prakan Sinsong.
A third colleague, Sgt Maj Yongyuth Panyanuwat, was wounded.
All were administrative clerks in the office, she said.
Sgt Maj Yongyuth was rushed to Phramongkutklao Hospital for emergency treatment.
After the shooting, Sgt Maj Yongyut left the college building and was arrested by police waiting in front of the Army Training Command building.
Sgt Maj Yongyut had been under strain and had health problems. He was also on record to have suffered from mental illness, said Col Sirichan, citing information obtained from the office.
She said police handling the case would receive full cooperation to ensure justice for all concerned.
"The army would like to extend its condolences to the families of those killed and injured. It is a big loss to both the army and those families," she said.
In February 2020, a soldier shot dead 29 people in a 17-hour rampage and wounded scores more before he was shot dead by commandos in Nakhon Ratchasima province.
That shooting was linked to a debt dispute between the gunman, Sgt Maj 1st Class Jakrapanth Thomma, 32, and a senior officer. The military top brass was at pains to portray the killer as a rogue soldier.